Identification of reduced-order model for an aeroelastic system from flutter test data
Wei Tang
2017-02-01
Full Text Available Recently, flutter active control using linear parameter varying (LPV framework has attracted a lot of attention. LPV control synthesis usually generates controllers that are at least of the same order as the aeroelastic models. Therefore, the reduced-order model is required by synthesis for avoidance of large computation cost and high-order controller. This paper proposes a new procedure for generation of accurate reduced-order linear time-invariant (LTI models by using system identification from flutter testing data. The proposed approach is in two steps. The well-known poly-reference least squares complex frequency (p-LSCF algorithm is firstly employed for modal parameter identification from frequency response measurement. After parameter identification, the dominant physical modes are determined by clear stabilization diagrams and clustering technique. In the second step, with prior knowledge of physical poles, the improved frequency-domain maximum likelihood (ML estimator is presented for building accurate reduced-order model. Before ML estimation, an improved subspace identification considering the poles constraint is also proposed for initializing the iterative procedure. Finally, the performance of the proposed procedure is validated by real flight flutter test data.
Regularized Reduced Order Models
Wells, David; Xie, Xuping; Iliescu, Traian
2015-01-01
This paper puts forth a regularization approach for the stabilization of proper orthogonal decomposition (POD) reduced order models (ROMs) for the numerical simulation of realistic flows. Two regularized ROMs (Reg-ROMs) are proposed: the Leray ROM (L-ROM) and the evolve-then-filter ROM (EF-ROM). These new Reg-ROMs use spatial filtering to smooth (regularize) various terms in the ROMs. Two spatial filters are used: a POD projection onto a POD subspace (Proj) and a new POD differential filter (DF). The four Reg-ROM/filter combinations are tested in the numerical simulation of the one-dimensional Burgers equation with a small diffusion coefficient and the three-dimensional flow past a circular cylinder at a low Reynolds number (Re = 100). Overall, the most accurate Reg-ROM/filter combination is EF-ROM-DF. Furthermore, the DF generally yields better results than Proj. Finally, the four Reg-ROM/filter combinations are computationally efficient and generally more accurate than the standard Galerkin ROM.
Thibes, Ronaldo
2016-01-01
We perform the canonical and path integral quantizations of a lower-order derivatives model describing Podolsky's generalized electrodynamics. The physical content of the model shows an auxiliary massive vector field coupled to the usual electromagnetic field. The equivalence with Podolsky's original model is studied at classical and quantum levels. Concerning the dynamical time evolution we obtain a theory with two first-class and two second-class constraints in phase space. We calculate explicitly the corresponding Dirac brackets involving both vector fields. We use the Senjanovic procedure to implement the second-class constraints and the Batalin-Fradkin-Vilkovisky path integral quantization scheme to deal with the symmetries generated by the first-class constraints. The physical interpretation of the results turns out to be simpler due to the reduced derivatives order permeating the equations of motion, Dirac brackets and effective action.
Yu-Min Shen
Full Text Available Ideally, thrombophilia testing should be tailored to the type of thrombotic event without the influence of anticoagulation therapy or acute phase effects which can give false positive results that may result in long term anticoagulation. However, thrombophilia testing is often performed routinely in unselected patients. We analyzed all consecutive thrombophilia testing orders during the months of October and November 2009 at an academic teaching institution. Information was extracted from electronic medical records for the following: indication, timing, comprehensiveness of tests, anticoagulation therapy at the time of testing, and confirmatory repeat testing, if any. Based on the findings of this analysis, we established local guidelines in May 2013 for appropriate thrombophilia testing, primarily to prevent testing during the acute thrombotic event or while the patient is on anticoagulation. We then evaluated ordering practices 22 months after guideline implementation. One hundred seventy-three patients were included in the study. Only 34% (58/173 had appropriate indications (unprovoked venous or arterial thrombosis or pregnancy losses. 51% (61/119 with an index clinical event were tested within one week of the event. Although 46% (79/173 were found to have abnormal results, only 46% of these had the abnormal tests repeated for confirmation with 54% potentially carrying a wrong diagnosis with long term anticoagulation. Twenty-two months after guideline implementation, there was an 84% reduction in ordered tests. Thus, this study revealed that a significant proportion of thrombophilia testing was inappropriately performed. We implemented local guidelines for thrombophilia testing for clinicians, resulting in a reduction in healthcare costs and improved patient care.
Ialongo, Cristiano; Porzio, Ottavia; Giambini, Ilio; Bernardini, Sergio
2016-06-01
The transition to total automation represents the greatest leap for a clinical laboratory, characterized by a totally new philosophy of process management. We have investigated the impact of total automation on core laboratory efficiency and its effects on the clinical services related to STAT tests. For this purpose, a 47-month retrospective study based on the analysis of 44,212 records of STAT cardiac troponin I (CTNI) tests was performed. The core laboratory reached a new efficiency level 3 months after the implementation of total automation. Median turnaround time (TAT) was reduced by 14.9±1.5 min for the emergency department (p < 0.01), reaching 41.6±1.2 min. In non-emergency departments, median TAT was reduced by 19.8±2.2 min (p < 0.01), reaching 52±1.3 min. There was no change in the volume of ordered STAT CTNI tests by the emergency department (p = 0.811), whereas for non-emergency departments there was a reduction of 115.7±50 monthly requests on average (p = 0.026). The volume of ordered tests decreased only in time frames of the regular shift following the morning round. Thus, total automation significantly improves the core laboratory efficiency in terms of TAT. As a consequence, the volume of STAT tests ordered by hospital departments (except for the emergency department) decreased due to reduced duplicated requests.
Approximate Deconvolution Reduced Order Modeling
Xie, Xuping; Wang, Zhu; Iliescu, Traian
2015-01-01
This paper proposes a large eddy simulation reduced order model(LES-ROM) framework for the numerical simulation of realistic flows. In this LES-ROM framework, the proper orthogonal decomposition(POD) is used to define the ROM basis and a POD differential filter is used to define the large ROM structures. An approximate deconvolution(AD) approach is used to solve the ROM closure problem and develop a new AD-ROM. This AD-ROM is tested in the numerical simulation of the one-dimensional Burgers equation with a small diffusion coefficient(10^{-3})
Smeding, Annique; Dumas, Florence; Loose, Florence; Régner, Isabelle
2013-01-01
In 2 field experiments, we relied on the very features of real testing situations--where both math and verbal tests are administered--to examine whether order of test administration can, by itself, create vs. alleviate stereotype threat (ST) effects on girls' math performance. We predicted that taking the math test before the verbal test would be…
Smeding, Annique; Dumas, Florence; Loose, Florence; Régner, Isabelle
2013-01-01
In 2 field experiments, we relied on the very features of real testing situations--where both math and verbal tests are administered--to examine whether order of test administration can, by itself, create vs. alleviate stereotype threat (ST) effects on girls' math performance. We predicted that taking the math test before the verbal test would be…
Determining Reduced Order Models for Optimal Stochastic Reduced Order Models
Bonney, Matthew S. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Brake, Matthew R.W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2015-08-01
The use of parameterized reduced order models(PROMs) within the stochastic reduced order model (SROM) framework is a logical progression for both methods. In this report, five different parameterized reduced order models are selected and critiqued against the other models along with truth model for the example of the Brake-Reuss beam. The models are: a Taylor series using finite difference, a proper orthogonal decomposition of the the output, a Craig-Bampton representation of the model, a method that uses Hyper-Dual numbers to determine the sensitivities, and a Meta-Model method that uses the Hyper-Dual results and constructs a polynomial curve to better represent the output data. The methods are compared against a parameter sweep and a distribution propagation where the first four statistical moments are used as a comparison. Each method produces very accurate results with the Craig-Bampton reduction having the least accurate results. The models are also compared based on time requirements for the evaluation of each model where the Meta- Model requires the least amount of time for computation by a significant amount. Each of the five models provided accurate results in a reasonable time frame. The determination of which model to use is dependent on the availability of the high-fidelity model and how many evaluations can be performed. Analysis of the output distribution is examined by using a large Monte-Carlo simulation along with a reduced simulation using Latin Hypercube and the stochastic reduced order model sampling technique. Both techniques produced accurate results. The stochastic reduced order modeling technique produced less error when compared to an exhaustive sampling for the majority of methods.
Generalized Reduced Order Model Generation Project
National Aeronautics and Space Administration — M4 Engineering proposes to develop a generalized reduced order model generation method. This method will allow for creation of reduced order aeroservoelastic state...
Optimizing Reduced-Order Transfer Functions
Spanos, John T.; Milman, Mark H.; Mingori, D. Lewis
1992-01-01
Transfer-function approximations made optimal in special least-squares sense. Algorithm computes reduced-order rational-fraction approximates to single-input/single-output transfer functions. Reduces amount of computation needed for such purposes as numerical simulation of dynamics and design of control subsystems.
Reduced order modeling of fluid/structure interaction.
Barone, Matthew Franklin; Kalashnikova, Irina; Segalman, Daniel Joseph; Brake, Matthew Robert
2009-11-01
This report describes work performed from October 2007 through September 2009 under the Sandia Laboratory Directed Research and Development project titled 'Reduced Order Modeling of Fluid/Structure Interaction.' This project addresses fundamental aspects of techniques for construction of predictive Reduced Order Models (ROMs). A ROM is defined as a model, derived from a sequence of high-fidelity simulations, that preserves the essential physics and predictive capability of the original simulations but at a much lower computational cost. Techniques are developed for construction of provably stable linear Galerkin projection ROMs for compressible fluid flow, including a method for enforcing boundary conditions that preserves numerical stability. A convergence proof and error estimates are given for this class of ROM, and the method is demonstrated on a series of model problems. A reduced order method, based on the method of quadratic components, for solving the von Karman nonlinear plate equations is developed and tested. This method is applied to the problem of nonlinear limit cycle oscillations encountered when the plate interacts with an adjacent supersonic flow. A stability-preserving method for coupling the linear fluid ROM with the structural dynamics model for the elastic plate is constructed and tested. Methods for constructing efficient ROMs for nonlinear fluid equations are developed and tested on a one-dimensional convection-diffusion-reaction equation. These methods are combined with a symmetrization approach to construct a ROM technique for application to the compressible Navier-Stokes equations.
Testing Consent Order for Sodium Cyanide
This document announces that EPA has signed an enforceable testing Consent Order with E.I. du Pont de Nemours and Company (DuPont), FMC Corporation (FMC), Degussa Corporation (Degussa), ICI Americas Incorporated (ICI), and Cyanco Company (Cyanco).
Testing Consent Order on Refractory Ceramic Fibers
This notice announces that EPA has signed signed an enforceable testing consent order under the Toxic Substances Control Act (TSCA), 15 U.S.C. section 2601 at seq., with three of the primary producers of refractory ceramic fibers (RCF).
Bilinear reduced order approximate model of parabolic distributed solar collectors
Elmetennani, Shahrazed
2015-07-01
This paper proposes a novel, low dimensional and accurate approximate model for the distributed parabolic solar collector, by means of a modified gaussian interpolation along the spatial domain. The proposed reduced model, taking the form of a low dimensional bilinear state representation, enables the reproduction of the heat transfer dynamics along the collector tube for system analysis. Moreover, presented as a reduced order bilinear state space model, the well established control theory for this class of systems can be applied. The approximation efficiency has been proven by several simulation tests, which have been performed considering parameters of the Acurex field with real external working conditions. Model accuracy has been evaluated by comparison to the analytical solution of the hyperbolic distributed model and its semi discretized approximation highlighting the benefits of using the proposed numerical scheme. Furthermore, model sensitivity to the different parameters of the gaussian interpolation has been studied.
Sliding Mode Control Design via Reduced Order Model Approach
无
2007-01-01
This paper presents a design of continuous-time sliding mode control for the higher order systems via reduced order model. It is shown that a continuous-time sliding mode control designed for the reduced order model gives similar performance for the higher order system. The method is illustrated by numerical examples. The paper also introduces a technique for design of a sliding surface such that the system satisfies a cost-optimality condition when on the sliding surface.
Using the Neumann series expansion for assembling Reduced Order Models
Nasisi S.
2014-06-01
Full Text Available An efficient method to remove the limitation in selecting the master degrees of freedom in a finite element model by means of a model order reduction is presented. A major difficulty of the Guyan reduction and IRS method (Improved Reduced System is represented by the need of appropriately select the master and slave degrees of freedom for the rate of convergence to be high. This study approaches the above limitation by using a particular arrangement of the rows and columns of the assembled matrices K and M and employing a combination between the IRS method and a variant of the analytical selection of masters presented in (Shah, V. N., Raymund, M., Analytical selection of masters for the reduced eigenvalue problem, International Journal for Numerical Methods in Engineering 18 (1 1982 in case first lowest frequencies had to be sought. One of the most significant characteristics of the approach is the use of the Neumann series expansion that motivates this particular arrangement of the matrices’ entries. The method shows a higher rate of convergence when compared to the standard IRS and very accurate results for the lowest reduced frequencies. To show the effectiveness of the proposed method two testing structures and the human vocal tract model employed in (Vampola, T., Horacek, J., Svec, J. G., FE modeling of human vocal tract acoustics. Part I: Prodution of Czech vowels, Acta Acustica United with Acustica 94 (3 2008 are presented.
Reduced order modeling of steady flows subject to aerodynamic constraints
Zimmermann, Ralf; Vendl, Alexander; Goertz, Stefan
2014-01-01
A novel reduced-order modeling method based on proper orthogonal decomposition for predicting steady, turbulent flows subject to aerodynamic constraints is introduced. Model-order reduction is achieved by replacing the governing equations of computational fluid dynamics with a nonlinear weighted ...
Construction of energy-stable Galerkin reduced order models.
Kalashnikova, Irina; Barone, Matthew Franklin; Arunajatesan, Srinivasan; van Bloemen Waanders, Bart Gustaaf
2013-05-01
This report aims to unify several approaches for building stable projection-based reduced order models (ROMs). Attention is focused on linear time-invariant (LTI) systems. The model reduction procedure consists of two steps: the computation of a reduced basis, and the projection of the governing partial differential equations (PDEs) onto this reduced basis. Two kinds of reduced bases are considered: the proper orthogonal decomposition (POD) basis and the balanced truncation basis. The projection step of the model reduction can be done in two ways: via continuous projection or via discrete projection. First, an approach for building energy-stable Galerkin ROMs for linear hyperbolic or incompletely parabolic systems of PDEs using continuous projection is proposed. The idea is to apply to the set of PDEs a transformation induced by the Lyapunov function for the system, and to build the ROM in the transformed variables. The resulting ROM will be energy-stable for any choice of reduced basis. It is shown that, for many PDE systems, the desired transformation is induced by a special weighted L2 inner product, termed the %E2%80%9Csymmetry inner product%E2%80%9D. Attention is then turned to building energy-stable ROMs via discrete projection. A discrete counterpart of the continuous symmetry inner product, a weighted L2 inner product termed the %E2%80%9CLyapunov inner product%E2%80%9D, is derived. The weighting matrix that defines the Lyapunov inner product can be computed in a black-box fashion for a stable LTI system arising from the discretization of a system of PDEs in space. It is shown that a ROM constructed via discrete projection using the Lyapunov inner product will be energy-stable for any choice of reduced basis. Connections between the Lyapunov inner product and the inner product induced by the balanced truncation algorithm are made. Comparisons are also made between the symmetry inner product and the Lyapunov inner product. The performance of ROMs constructed
Reduced order modeling of some fluid flows of industrial interest
Alonso, D; Terragni, F; Velazquez, A; Vega, J M, E-mail: josemanuel.vega@upm.es [E.T.S.I. Aeronauticos, Universidad Politecnica de Madrid, 28040 Madrid (Spain)
2012-06-01
Some basic ideas are presented for the construction of robust, computationally efficient reduced order models amenable to be used in industrial environments, combined with somewhat rough computational fluid dynamics solvers. These ideas result from a critical review of the basic principles of proper orthogonal decomposition-based reduced order modeling of both steady and unsteady fluid flows. In particular, the extent to which some artifacts of the computational fluid dynamics solvers can be ignored is addressed, which opens up the possibility of obtaining quite flexible reduced order models. The methods are illustrated with the steady aerodynamic flow around a horizontal tail plane of a commercial aircraft in transonic conditions, and the unsteady lid-driven cavity problem. In both cases, the approximations are fairly good, thus reducing the computational cost by a significant factor. (review)
Two-step greedy algorithm for reduced order quadratures
Antil, Harbir; Herrmann, Frank; Nochetto, Ricardo H; Tiglio, Manuel
2012-01-01
We present an algorithm to generate application-specific, global reduced order quadratures (ROQ) for multiple fast evaluations of weighted inner products between parameterized functions. If a reduced basis (RB) or any other projection-based model reduction technique is applied, the dimensionality of integrands is reduced dramatically; however, the cost of evaluating the reduced integrals still scales as the size of the original problem. In contrast, using discrete empirical interpolation (DEIM) points as ROQ nodes leads to a computational cost which depends linearly on the dimension of the reduced space. Generation of a reduced basis via a greedy procedure requires a training set, which for products of functions can be very large. Since this direct approach can be impractical in many applications, we propose instead a two-step greedy targeted towards approximation of such products. We present numerical experiments demonstrating the accuracy and the efficiency of the two-step approach. The presented ROQ are ex...
Reduced-order Kalman filtering with incomplete observability
Yonezawa, K.
1980-01-01
Kalman filtering is considered with reference to linear stochastic dynamic systems without complete observability. It is shown that the canonical decomposition theorem can be extended to the stochastic case and the matrix Riccati equation of the Kalman filter is order-reducible if some states are not observable. The inclusion of unobservable states in Kalman filtering makes the unobservable states 'asymptotically' observable in the filter if these unobservable states are dynamically connected to observable states and asymptotically stable. The reduced-order Kalman filter saves computation time when compared to the conventional Kalman filter.
Projection-Based Reduced Order Modeling for Spacecraft Thermal Analysis
Qian, Jing; Wang, Yi; Song, Hongjun; Pant, Kapil; Peabody, Hume; Ku, Jentung; Butler, Charles D.
2015-01-01
This paper presents a mathematically rigorous, subspace projection-based reduced order modeling (ROM) methodology and an integrated framework to automatically generate reduced order models for spacecraft thermal analysis. Two key steps in the reduced order modeling procedure are described: (1) the acquisition of a full-scale spacecraft model in the ordinary differential equation (ODE) and differential algebraic equation (DAE) form to resolve its dynamic thermal behavior; and (2) the ROM to markedly reduce the dimension of the full-scale model. Specifically, proper orthogonal decomposition (POD) in conjunction with discrete empirical interpolation method (DEIM) and trajectory piece-wise linear (TPWL) methods are developed to address the strong nonlinear thermal effects due to coupled conductive and radiative heat transfer in the spacecraft environment. Case studies using NASA-relevant satellite models are undertaken to verify the capability and to assess the computational performance of the ROM technique in terms of speed-up and error relative to the full-scale model. ROM exhibits excellent agreement in spatiotemporal thermal profiles (<0.5% relative error in pertinent time scales) along with salient computational acceleration (up to two orders of magnitude speed-up) over the full-scale analysis. These findings establish the feasibility of ROM to perform rational and computationally affordable thermal analysis, develop reliable thermal control strategies for spacecraft, and greatly reduce the development cycle times and costs.
A reduced order model for nonlinear vibroacoustic problems
Ouisse Morvan
2012-07-01
Full Text Available This work is related to geometrical nonlinearities applied to thin plates coupled with fluid-filled domain. Model reduction is performed to reduce the computation time. Reduced order model (ROM is issued from the uncoupled linear problem and enriched with residues to describe the nonlinear behavior and coupling effects. To show the efficiency of the proposed method, numerical simulations in the case of an elastic plate closing an acoustic cavity are presented.
Reduced Order Internal Models in the Frequency Domain
Laakkonen, Petteri; Paunonen, Lassi
2016-01-01
The internal model principle states that all robustly regulating controllers must contain a suitably reduplicated internal model of the signal to be regulated. Using frequency domain methods, we show that the number of the copies may be reduced if the class of perturbations in the problem is restricted. We present a two step design procedure for a simple controller containing a reduced order internal model achieving robust regulation. The results are illustrated with an example of a five tank...
Reduced Order Dead-Beat Observers for a Bioreactor
Karafyllis, Iasson
2010-01-01
This paper studies the strong observability property and the reduced-order dead-beat observer design problem for a continuous bioreactor. New relationships between coexistence and strong observability, and checkable sufficient conditions for strong observability, are established for a chemostat with two competing microbial species. Furthermore, the dynamic output feedback stabilization problem is solved for the case of one species.
Reduced-order models for vertical human-structure interaction
Van Nimmen, Katrien; Lombaert, Geert; De Roeck, Guido; Van den Broeck, Peter
2016-09-01
For slender and lightweight structures, the vibration serviceability under crowd- induced loading is often critical in design. Currently, designers rely on equivalent load models, upscaled from single-person force measurements. Furthermore, it is important to consider the mechanical interaction with the human body as this can significantly reduce the structural response. To account for these interaction effects, the contact force between the pedestrian and the structure can be modelled as the superposition of the force induced by the pedestrian on a rigid floor and the force resulting from the mechanical interaction between the structure and the human body. For the case of large crowds, however, this approach leads to models with a very high system order. In the present contribution, two equivalent reduced-order models are proposed to approximate the dynamic behaviour of the full-order coupled crowd-structure system. A numerical study is performed to evaluate the impact of the modelling assumptions on the structural response to pedestrian excitation. The results show that the full-order moving crowd model can be well approximated by a reduced-order model whereby the interaction with the pedestrians in the crowd is modelled using a single (equivalent) SDOF system.
Reduced order modeling of grid-connected photovoltaic inverter systems
Wasynczuk, O.; Krause, P. C.; Anwah, N. A.
1988-04-01
This report summarizes the development of reduced order models of three-phase, line- and self-commutated inverter systems. This work was performed as part of the National Photovoltaics Program within the United States Department of Energy and was supervised by Sandia National Laboratories. The overall objective of the national program is to promote the development of low cost, reliable terrestrial photovoltaic systems for widespread use in residential, commercial and utility applications. The purpose of the effort reported herein is to provide reduced order models of three-phase, line- and self-commutated PV systems suitable for implementation into transient stability programs, which are commonly used to predict the stability characteristics of large-scale power systems. The accuracy of the reduced models is verified by comparing the response characteristics predicted therefrom with the response established using highly detailed PV system models in which the inverter switching is represented in detail.
Reduced density matrix and order parameters of a topological insulator
Yu, Wing Chi; Li, Yan Chao; Sacramento, P. D.; Lin, Hai-Qing
2016-12-01
It has been recently proposed that the reduced density matrix may be used to derive the order parameter of a condensed matter system. Here we propose order parameters for the phases of a topological insulator, specifically a spinless Su-Schrieffer-Heeger (SSH) model, and consider the effect of short-range interactions. All the derived order parameters and their possible corresponding quantum phases are verified by the entanglement entropy and electronic configuration analysis results. The order parameter appropriate to the topological regions is further proved by calculating the Berry phase under twisted boundary conditions. It is found that the topological nontrivial phase is robust to the introduction of repulsive intersite interactions and can appear in the topological trivial parameter region when appropriate interactions are added.
AN OVERVIEW OF REDUCED ORDER MODELING TECHNIQUES FOR SAFETY APPLICATIONS
Mandelli, D.; Alfonsi, A.; Talbot, P.; Wang, C.; Maljovec, D.; Smith, C.; Rabiti, C.; Cogliati, J.
2016-10-01
The RISMC project is developing new advanced simulation-based tools to perform Computational Risk Analysis (CRA) for the existing fleet of U.S. nuclear power plants (NPPs). These tools numerically model not only the thermal-hydraulic behavior of the reactors primary and secondary systems, but also external event temporal evolution and component/system ageing. Thus, this is not only a multi-physics problem being addressed, but also a multi-scale problem (both spatial, µm-mm-m, and temporal, seconds-hours-years). As part of the RISMC CRA approach, a large amount of computationally-expensive simulation runs may be required. An important aspect is that even though computational power is growing, the overall computational cost of a RISMC analysis using brute-force methods may be not viable for certain cases. A solution that is being evaluated to assist the computational issue is the use of reduced order modeling techniques. During the FY2015, we investigated and applied reduced order modeling techniques to decrease the RISMC analysis computational cost by decreasing the number of simulation runs; for this analysis improvement we used surrogate models instead of the actual simulation codes. This article focuses on the use of reduced order modeling techniques that can be applied to RISMC analyses in order to generate, analyze, and visualize data. In particular, we focus on surrogate models that approximate the simulation results but in a much faster time (microseconds instead of hours/days).
Parameterized reduced-order models using hyper-dual numbers.
Fike, Jeffrey A.; Brake, Matthew Robert
2013-10-01
The goal of most computational simulations is to accurately predict the behavior of a real, physical system. Accurate predictions often require very computationally expensive analyses and so reduced order models (ROMs) are commonly used. ROMs aim to reduce the computational cost of the simulations while still providing accurate results by including all of the salient physics of the real system in the ROM. However, real, physical systems often deviate from the idealized models used in simulations due to variations in manufacturing or other factors. One approach to this issue is to create a parameterized model in order to characterize the effect of perturbations from the nominal model on the behavior of the system. This report presents a methodology for developing parameterized ROMs, which is based on Craig-Bampton component mode synthesis and the use of hyper-dual numbers to calculate the derivatives necessary for the parameterization.
Accelerating transient simulation of linear reduced order models.
Thornquist, Heidi K.; Mei, Ting; Keiter, Eric Richard; Bond, Brad
2011-10-01
Model order reduction (MOR) techniques have been used to facilitate the analysis of dynamical systems for many years. Although existing model reduction techniques are capable of providing huge speedups in the frequency domain analysis (i.e. AC response) of linear systems, such speedups are often not obtained when performing transient analysis on the systems, particularly when coupled with other circuit components. Reduced system size, which is the ostensible goal of MOR methods, is often insufficient to improve transient simulation speed on realistic circuit problems. It can be shown that making the correct reduced order model (ROM) implementation choices is crucial to the practical application of MOR methods. In this report we investigate methods for accelerating the simulation of circuits containing ROM blocks using the circuit simulator Xyce.
Reduced order ARMA spectral estimation of ocean waves
Mandal, S.; Witz, J.A.; Lyons, G.J.
Autoregressive Moving Average (ARMA) algorithm which is based on the calculation of modal energies. We apply this system identification technique to reduce time series data or target spectra into a few parameters which are the coefficients of the ARMA model... are determined using the modified Yule-Walker equations and then first and second order real modes are obtained from the autoregressive polynomial. The energy in each mode is then determined. Considering only the higher energy modes, the autoregressive part...
Regularization method for calibrated POD reduced-order models
El Majd Badr Abou
2014-01-01
Full Text Available In this work we present a regularization method to improve the accuracy of reduced-order models based on Proper Orthogonal Decomposition. The bench mark configuration retained corresponds to a case of relatively simple dynamics: a two-dimensional flow around a cylinder for a Reynolds number of 200. Finally, we show for this flow configuration that this procedure is efficient in term of reduction of errors.
On the verification of PGD reduced-order models
Pled, Florent; Chamoin, Ludovic; Ladevèze, Pierre
2014-01-01
International audience; In current computational mechanics practice, multidimensional as well as multiscale or parametric models encountered in a wide variety of scientific and engineering fields often require either the resolution of significantly large complexity problems or the direct calculation of very numerous solutions of such complex models. In this framework, the use of model order reduction allows to dramatically reduce the computational requirements engendered by the increasing mod...
Robust simulation of buckled structures using reduced order modeling
Wiebe, R.; Perez, R. A.; Spottswood, S. M.
2016-09-01
Lightweight metallic structures are a mainstay in aerospace engineering. For these structures, stability, rather than strength, is often the critical limit state in design. For example, buckling of panels and stiffeners may occur during emergency high-g maneuvers, while in supersonic and hypersonic aircraft, it may be induced by thermal stresses. The longstanding solution to such challenges was to increase the sizing of the structural members, which is counter to the ever present need to minimize weight for reasons of efficiency and performance. In this work we present some recent results in the area of reduced order modeling of post- buckled thin beams. A thorough parametric study of the response of a beam to changing harmonic loading parameters, which is useful in exposing complex phenomena and exercising numerical models, is presented. Two error metrics that use but require no time stepping of a (computationally expensive) truth model are also introduced. The error metrics are applied to several interesting forcing parameter cases identified from the parametric study and are shown to yield useful information about the quality of a candidate reduced order model. Parametric studies, especially when considering forcing and structural geometry parameters, coupled environments, and uncertainties would be computationally intractable with finite element models. The goal is to make rapid simulation of complex nonlinear dynamic behavior possible for distributed systems via fast and accurate reduced order models. This ability is crucial in allowing designers to rigorously probe the robustness of their designs to account for variations in loading, structural imperfections, and other uncertainties.
Advanced Fluid Reduced Order Models for Compressible Flow.
Tezaur, Irina Kalashnikova; Fike, Jeffrey A.; Carlberg, Kevin Thomas; Barone, Matthew F.; Maddix, Danielle; Mussoni, Erin E.; Balajewicz, Maciej (UIUC)
2017-09-01
This report summarizes fiscal year (FY) 2017 progress towards developing and implementing within the SPARC in-house finite volume flow solver advanced fluid reduced order models (ROMs) for compressible captive-carriage flow problems of interest to Sandia National Laboratories for the design and qualification of nuclear weapons components. The proposed projection-based model order reduction (MOR) approach, known as the Proper Orthogonal Decomposition (POD)/Least- Squares Petrov-Galerkin (LSPG) method, can substantially reduce the CPU-time requirement for these simulations, thereby enabling advanced analyses such as uncertainty quantification and de- sign optimization. Following a description of the project objectives and FY17 targets, we overview briefly the POD/LSPG approach to model reduction implemented within SPARC . We then study the viability of these ROMs for long-time predictive simulations in the context of a two-dimensional viscous laminar cavity problem, and describe some FY17 enhancements to the proposed model reduction methodology that led to ROMs with improved predictive capabilities. Also described in this report are some FY17 efforts pursued in parallel to the primary objective of determining whether the ROMs in SPARC are viable for the targeted application. These include the implemen- tation and verification of some higher-order finite volume discretization methods within SPARC (towards using the code to study the viability of ROMs on three-dimensional cavity problems) and a novel structure-preserving constrained POD/LSPG formulation that can improve the accuracy of projection-based reduced order models. We conclude the report by summarizing the key takeaways from our FY17 findings, and providing some perspectives for future work.
Accelerated gravitational wave parameter estimation with reduced order modeling.
Canizares, Priscilla; Field, Scott E; Gair, Jonathan; Raymond, Vivien; Smith, Rory; Tiglio, Manuel
2015-02-20
Inferring the astrophysical parameters of coalescing compact binaries is a key science goal of the upcoming advanced LIGO-Virgo gravitational-wave detector network and, more generally, gravitational-wave astronomy. However, current approaches to parameter estimation for these detectors require computationally expensive algorithms. Therefore, there is a pressing need for new, fast, and accurate Bayesian inference techniques. In this Letter, we demonstrate that a reduced order modeling approach enables rapid parameter estimation to be performed. By implementing a reduced order quadrature scheme within the LIGO Algorithm Library, we show that Bayesian inference on the 9-dimensional parameter space of nonspinning binary neutron star inspirals can be sped up by a factor of ∼30 for the early advanced detectors' configurations (with sensitivities down to around 40 Hz) and ∼70 for sensitivities down to around 20 Hz. This speedup will increase to about 150 as the detectors improve their low-frequency limit to 10 Hz, reducing to hours analyses which could otherwise take months to complete. Although these results focus on interferometric gravitational wave detectors, the techniques are broadly applicable to any experiment where fast Bayesian analysis is desirable.
Reduced-Order Kalman Filtering for Processing Relative Measurements
Bayard, David S.
2008-01-01
A study in Kalman-filter theory has led to a method of processing relative measurements to estimate the current state of a physical system, using less computation than has previously been thought necessary. As used here, relative measurements signifies measurements that yield information on the relationship between a later and an earlier state of the system. An important example of relative measurements arises in computer vision: Information on relative motion is extracted by comparing images taken at two different times. Relative measurements do not directly fit into standard Kalman filter theory, in which measurements are restricted to those indicative of only the current state of the system. One approach heretofore followed in utilizing relative measurements in Kalman filtering, denoted state augmentation, involves augmenting the state of the system at the earlier of two time instants and then propagating the state to the later time instant.While state augmentation is conceptually simple, it can also be computationally prohibitive because it doubles the number of states in the Kalman filter. When processing a relative measurement, if one were to follow the state-augmentation approach as practiced heretofore, one would find it necessary to propagate the full augmented state Kalman filter from the earlier time to the later time and then select out the reduced-order components. The main result of the study reported here is proof of a property called reduced-order equivalence (ROE). The main consequence of ROE is that it is not necessary to augment with the full state, but, rather, only the portion of the state that is explicitly used in the partial relative measurement. In other words, it suffices to select the reduced-order components first and then propagate the partial augmented state Kalman filter from the earlier time to the later time; the amount of computation needed to do this can be substantially less than that needed for propagating the full augmented
Reduced order multiport parallel and multidirectional neural associative memories.
Bhatti, Abdul Aziz
2009-05-01
This paper proposes multiport parallel and multidirectional intraconnected associative memories of outer product type with reduced interconnections. Some new reduced order memory architectures such as k-directional and k-port parallel memories are suggested. These architectures are, also, very suitable for implementation of spatio-temporal sequences and multiassociative memories. It is shown that in the proposed memory architectures, a substational reduction in interconnections is achieved if the actual length of original N-bit long vectors is subdivided into k sublengths. Using these sublengths, submemory matrices, T ( s ) or W ( s ), are computed, which are then intraconnected to form k-port parallel or k-directional memories. The subdivisions of N-bit long vectors into k sublengths save ((k-1) x 100) / k % of interconnections. It is shown, by means of an example, that more than 80% reduction in interconnections is achieved. Minimum limit in bits on k as well as maximum limit on subdivisions in k is determined. The topologies of reduced interconnectivity developed in this paper are symmetric in structure and can be used to scale up to larger systems. The underlying principal of construction, storage and retrieval processes of such associative memories has been analyzed. The effect of complexity of different levels of reduced interconnectivity on the quality of retrieval, signal to noise ratio, and storage capacity has been investigated. The model possesses analogies to biological neural structures and digital parallel port memories commonly used in parallel and multiprocessing systems.
Computational design of patterned interfaces using reduced order models
Vattré, A. J.; Abdolrahim, N.; Kolluri, K.; Demkowicz, M. J.
2014-01-01
Patterning is a familiar approach for imparting novel functionalities to free surfaces. We extend the patterning paradigm to interfaces between crystalline solids. Many interfaces have non-uniform internal structures comprised of misfit dislocations, which in turn govern interface properties. We develop and validate a computational strategy for designing interfaces with controlled misfit dislocation patterns by tailoring interface crystallography and composition. Our approach relies on a novel method for predicting the internal structure of interfaces: rather than obtaining it from resource-intensive atomistic simulations, we compute it using an efficient reduced order model based on anisotropic elasticity theory. Moreover, our strategy incorporates interface synthesis as a constraint on the design process. As an illustration, we apply our approach to the design of interfaces with rapid, 1-D point defect diffusion. Patterned interfaces may be integrated into the microstructure of composite materials, markedly improving performance. PMID:25169868
Reduced order methods for modeling and computational reduction
Rozza, Gianluigi
2014-01-01
This monograph addresses the state of the art of reduced order methods for modeling and computational reduction of complex parametrized systems, governed by ordinary and/or partial differential equations, with a special emphasis on real time computing techniques and applications in computational mechanics, bioengineering and computer graphics. Several topics are covered, including: design, optimization, and control theory in real-time with applications in engineering; data assimilation, geometry registration, and parameter estimation with special attention to real-time computing in biomedical engineering and computational physics; real-time visualization of physics-based simulations in computer science; the treatment of high-dimensional problems in state space, physical space, or parameter space; the interactions between different model reduction and dimensionality reduction approaches; the development of general error estimation frameworks which take into account both model and discretization effects. This...
An improved model for reduced-order physiological fluid flows
San, Omer; 10.1142/S0219519411004666
2012-01-01
An improved one-dimensional mathematical model based on Pulsed Flow Equations (PFE) is derived by integrating the axial component of the momentum equation over the transient Womersley velocity profile, providing a dynamic momentum equation whose coefficients are smoothly varying functions of the spatial variable. The resulting momentum equation along with the continuity equation and pressure-area relation form our reduced-order model for physiological fluid flows in one dimension, and are aimed at providing accurate and fast-to-compute global models for physiological systems represented as networks of quasi one-dimensional fluid flows. The consequent nonlinear coupled system of equations is solved by the Lax-Wendroff scheme and is then applied to an open model arterial network of the human vascular system containing the largest fifty-five arteries. The proposed model with functional coefficients is compared with current classical one-dimensional theories which assume steady state Hagen-Poiseuille velocity pro...
Reduced order observer based identification of base isolated buildings
Satish Nagarajaiah; Prasad Dharap
2003-01-01
The objective of this study is to identify system parameters from the recorded response of base isolated buildings, such as USC hospital building, during the 1994 Northridge earthquake. Full state measurements are not available for identification. Additionally, the response is nonlinear due to the yielding of the lead-rubber bearings. Two new approaches are presented in this paper to solve the aforementioned problems. First, a reduced order observer is used to estimate the unmeasured states. Second, a least squares technique with time segments is developed to identify the piece-wise linear system properties. The observer is used to estimate the initial conditions needed for the time segmented identification. A series of equivalent linear system parameters are identified in different time segments. It is shown that the change in system parameters, such as frequencies and damping ratios, due to nonlinear behavior of the lead-rubber bearings, are reliably estimated using the presented technique. It is shown that the response was reduced due to yielding of the lead-rubber bearings and period lengthening.
Reduced order modeling in iTOUGH2
Pau, George Shu Heng; Zhang, Yingqi; Finsterle, Stefan; Wainwright, Haruko; Birkholzer, Jens
2014-04-01
The inverse modeling and uncertainty quantification capabilities of iTOUGH2 are augmented with reduced order models (ROMs) that act as efficient surrogates for computationally expensive high fidelity models (HFMs). The implementation of the ROM capabilities involves integration of three main computational components. The first component is the ROM itself. Two response surface approximations are currently implemented: Gaussian process regression (GPR) and radial basis function (RBF) interpolation. The second component is a multi-output adaptive sampling procedure that determines the sample points used to construct the ROMs. The third component involves defining appropriate error measures for the adaptive sampling procedure, allowing ROMs to be constructed efficiently with limited user intervention. Details in all three components must complement one another to obtain an accurate approximation. The new capability and its integration with other analysis tools within iTOUGH2 are demonstrated in two examples. The results from using the ROMs in an uncertainty quantification analysis and a global sensitivity analysis compare favorably with the results obtained using the HFMs. GPR is more accurate than RBF, but the difference can be small and similar conclusion can be deduced from the analyses. In the second example involving a realistic numerical model for a hypothetical industrial-scale carbon storage project in the Southern San Joaquin Basin, California, USA, significant reduction in computational effort can be achieved when ROMs are used to perform a rigorous global sensitivity analysis.
Empirical Reduced-Order Modeling for Boundary Feedback Flow Control
Seddik M. Djouadi
2008-01-01
Full Text Available This paper deals with the practical and theoretical implications of model reduction for aerodynamic flow-based control problems. Various aspects of model reduction are discussed that apply to partial differential equation- (PDE- based models in general. Specifically, the proper orthogonal decomposition (POD of a high dimension system as well as frequency domain identification methods are discussed for initial model construction. Projections on the POD basis give a nonlinear Galerkin model. Then, a model reduction method based on empirical balanced truncation is developed and applied to the Galerkin model. The rationale for doing so is that linear subspace approximations to exact submanifolds associated with nonlinear controllability and observability require only standard matrix manipulations utilizing simulation/experimental data. The proposed method uses a chirp signal as input to produce the output in the eigensystem realization algorithm (ERA. This method estimates the system's Markov parameters that accurately reproduce the output. Balanced truncation is used to show that model reduction is still effective on ERA produced approximated systems. The method is applied to a prototype convective flow on obstacle geometry. An H∞ feedback flow controller is designed based on the reduced model to achieve tracking and then applied to the full-order model with excellent performance.
Stochastic reduced order models for inverse problems under uncertainty.
Warner, James E; Aquino, Wilkins; Grigoriu, Mircea D
2015-03-01
This work presents a novel methodology for solving inverse problems under uncertainty using stochastic reduced order models (SROMs). Given statistical information about an observed state variable in a system, unknown parameters are estimated probabilistically through the solution of a model-constrained, stochastic optimization problem. The point of departure and crux of the proposed framework is the representation of a random quantity using a SROM - a low dimensional, discrete approximation to a continuous random element that permits e cient and non-intrusive stochastic computations. Characterizing the uncertainties with SROMs transforms the stochastic optimization problem into a deterministic one. The non-intrusive nature of SROMs facilitates e cient gradient computations for random vector unknowns and relies entirely on calls to existing deterministic solvers. Furthermore, the method is naturally extended to handle multiple sources of uncertainty in cases where state variable data, system parameters, and boundary conditions are all considered random. The new and widely-applicable SROM framework is formulated for a general stochastic optimization problem in terms of an abstract objective function and constraining model. For demonstration purposes, however, we study its performance in the specific case of inverse identification of random material parameters in elastodynamics. We demonstrate the ability to efficiently recover random shear moduli given material displacement statistics as input data. We also show that the approach remains effective for the case where the loading in the problem is random as well.
Proposed production test for reducing minimum downtime
Jaklevick, J.F.
1961-11-29
The object of the production test described in this report is to evaluate the operational aspects of a proposed method for reducing minimum downtime. The excess xenon poisoning, which occurs during the first 32--38 hours after the shutdown of a reactor from present equilibrium levels, will be partially overridden by a central enriched zone whose added reactivity contribution would be compensated during normal operation by means of poison splines.
Interventions to Educate Family Physicians to Change Test Ordering
Roger Edmund Thomas MD, PhD, CCFP, MRCGP
2016-03-01
Full Text Available The purpose is to systematically review randomised controlled trials (RCTs to change family physicians’ laboratory test-ordering. We searched 15 electronic databases (no language/date limitations. We identified 29 RCTs (4,111 physicians, 175,563 patients. Six studies specifically focused on reducing unnecessary tests, 23 on increasing screening tests. Using Cochrane methodology 48.5% of studies were low risk-of-bias for randomisation, 7% concealment of randomisation, 17% blinding of participants/personnel, 21% blinding outcome assessors, 27.5% attrition, 93% selective reporting. Only six studies were low risk for both randomisation and attrition. Twelve studies performed a power computation, three an intention-to-treat analysis and 13 statistically controlled clustering. Unweighted averages were computed to compare intervention/control groups for tests assessed by >5 studies. The results were that fourteen studies assessed lipids (average 10% more tests than control, 14 diabetes (average 8% > control, 5 cervical smears, 2 INR, one each thyroid, fecal occult-blood, cotinine, throat-swabs, testing after prescribing, and urine-cultures. Six studies aimed to decrease test groups (average decrease 18%, and two to increase test groups. Intervention strategies: one study used education (no change: two feedback (one 5% increase, one 27% desired decrease; eight education + feedback (average increase in desired direction >control 4.9%, ten system change (average increase 14.9%, one system change + feedback (increases 5-44%, three education + system change (average increase 6%, three education + system change + feedback (average 7.7% increase, one delayed testing. The conclusions are that only six RCTs were assessed at low risk of bias from both randomisation and attrition. Nevertheless, despite methodological shortcomings studies that found large changes (e.g. >20% probably obtained real change.
A proposed Fast algorithm to construct the system matrices for a reduced-order groundwater model
Ushijima, Timothy T.; Yeh, William W.-G.
2017-04-01
Past research has demonstrated that a reduced-order model (ROM) can be two-to-three orders of magnitude smaller than the original model and run considerably faster with acceptable error. A standard method to construct the system matrices for a ROM is Proper Orthogonal Decomposition (POD), which projects the system matrices from the full model space onto a subspace whose range spans the full model space but has a much smaller dimension than the full model space. This projection can be prohibitively expensive to compute if it must be done repeatedly, as with a Monte Carlo simulation. We propose a Fast Algorithm to reduce the computational burden of constructing the system matrices for a parameterized, reduced-order groundwater model (i.e. one whose parameters are represented by zones or interpolation functions). The proposed algorithm decomposes the expensive system matrix projection into a set of simple scalar-matrix multiplications. This allows the algorithm to efficiently construct the system matrices of a POD reduced-order model at a significantly reduced computational cost compared with the standard projection-based method. The developed algorithm is applied to three test cases for demonstration purposes. The first test case is a small, two-dimensional, zoned-parameter, finite-difference model; the second test case is a small, two-dimensional, interpolated-parameter, finite-difference model; and the third test case is a realistically-scaled, two-dimensional, zoned-parameter, finite-element model. In each case, the algorithm is able to accurately and efficiently construct the system matrices of the reduced-order model.
A reduced-order method for estimating the stability region of power systems with saturated controls
GAN; DeQiang; XIN; HuanHai; QIU; JiaJu; HAN; ZhenXiang
2007-01-01
In a modern power system, there is often large difference in the decay speeds of transients. This could lead to numerical problems such as heavy simulation burden and singularity when the traditional methods are used to estimate the stability region of such a dynamic system with saturation nonlinearities. To overcome these problems, a reduced-order method, based on the singular perturbation theory, is suggested to estimate the stability region of a singular system with saturation nonlinearities. In the reduced-order method, a low-order linear dynamic system with saturation nonlinearities is constructed to estimate the stability region of the primary high-order system so that the singularity is eliminated and the estimation process is simplified. In addition, the analytical foundation of the reduction method is proven and the method is validated using a test power system with 3 buses and 5 machines.
40 CFR 86.603-88 - Test orders.
2010-07-01
... Auditing of New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.603-88 Test orders. (a... utilize only those tools and test equipment utilized by its dealers when performing authorized...
Reduced Order Models for Dynamic Behavior of Elastomer Damping Devices
Morin, B.; Legay, A.; Deü, J.-F.
2016-09-01
In the context of passive damping, various mechanical systems from the space industry use elastomer components (shock absorbers, silent blocks, flexible joints...). The material of these devices has frequency, temperature and amplitude dependent characteristics. The associated numerical models, using viscoelastic and hyperelastic constitutive behaviour, may become computationally too expensive during a design process. The aim of this work is to propose efficient reduced viscoelastic models of rubber devices. The first step is to choose an accurate material model that represent the viscoelasticity. The second step is to reduce the rubber device finite element model to a super-element that keeps the frequency dependence. This reduced model is first built by taking into account the fact that the device's interfaces are much more rigid than the rubber core. To make use of this difference, kinematical constraints enforce the rigid body motion of these interfaces reducing the rubber device model to twelve dofs only on the interfaces (three rotations and three translations per face). Then, the superelement is built by using a component mode synthesis method. As an application, the dynamic behavior of a structure supported by four hourglass shaped rubber devices under harmonic loads is analysed to show the efficiency of the proposed approach.
A Reduced Order, One Dimensional Model of Joint Response
DOHNER,JEFFREY L.
2000-11-06
As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.
Zhang, Wei; Su, Housheng; Wang, Hongwei; Han, Zhengzhi
2012-12-01
This paper aims to design full-order and reduced-order observers for one-sided Lipschitz nonlinear systems. The system under consideration is an extension of its known Lipschitz counterpart and possesses inherent advantages with respect to conservativeness. For such system, we first develop a novel Riccati equation approach to design a full-order observer, for which rigorous mathematical analysis is performed. Consequently, we show that the conditions under which a full-order observer exists also guarantee the existence of a reduced-order observer. A design method for the reduced-order observer that is dependent on the solution of the Riccati equation is then presented. The proposed conditions are easily and numerically tractable via standard numerical software. Furthermore, it is theoretically proven that the obtained conditions are less conservative than some existing ones in recent literature. The effectiveness of the proposed observers is illustrated via a simulative example.
Dibasic Esters; Final Enforceable Consent Agreement and Testing Consent Order
Under section 4 of the Toxic Substances Control Act (TSCA), EPA has issued a testing consent order (Order) that incorporates an enforceable consent agreement (ECA) with the Aceto Corporation, E.I. du Pont de Nemours and Company, and Solutia Inc.
2011-12-01
in the structural response of the panel. The damping comes from different sources, such as from the boundary conditions in the form of frictional ...exhaust nozzle due to the limited amount of working space between the nozzle and the facility exhaust duct. An overhead chain hoist as well as an...additional horizontally mounted come-along hoist were required to move the test article into place on the test fixture. The installation/removal set-up is
POD-Galerkin reduced-order modeling with adaptive finite element snapshots
Ullmann, Sebastian; Rotkvic, Marko; Lang, Jens
2016-11-01
We consider model order reduction by proper orthogonal decomposition (POD) for parametrized partial differential equations, where the underlying snapshots are computed with adaptive finite elements. We address computational and theoretical issues arising from the fact that the snapshots are members of different finite element spaces. We propose a method to create a POD-Galerkin model without interpolating the snapshots onto their common finite element mesh. The error of the reduced-order solution is not necessarily Galerkin orthogonal to the reduced space created from space-adapted snapshot. We analyze how this influences the error assessment for POD-Galerkin models of linear elliptic boundary value problems. As a numerical example we consider a two-dimensional convection-diffusion equation with a parametrized convective direction. To illustrate the applicability of our techniques to non-linear time-dependent problems, we present a test case of a two-dimensional viscous Burgers equation with parametrized initial data.
New EPA Guidance for Testing Pesticides Will Reduce Animal Testing
EPA is issuing guidance for requesting waivers of acute dermal toxicity testing requirements for pesticide formulations, which will lead to fewer animal tests for acute dermal toxicity for pesticides.
Generalized reduced-order synchronization of chaotic system based on fast slide mode
Gao Tie-Gang; Chen Zeng-Qiang; Yuan Zhu-Zhi
2005-01-01
A new kind of generalized reduced-order synchronization of different chaotic systems is proposed in this paper.It is shown that dynamical evolution of third-order oscillator can be synchronized with the canonical projection of a fourth-order chaotic system generated through nonsingular states transformation from a cell neural net chaotic system.In this sense, it is said that generalized synchronization is achieved in reduced-order. The synchronization discussed here expands the scope of reduced-order synchronization studied in relevant literatures. In this way, we can achieve generalized reduced-order synchronization between many famous chaotic systems such as the second-order D(u)ffing system and the third-order Lorenz system by designing a fast slide mode controller. Simulation results are provided to verify the operation of the designed synchronization.
Reduced order models for thermal analysis : final report : LDRD Project No. 137807.
Hogan, Roy E., Jr.; Gartling, David K.
2010-09-01
This LDRD Senior's Council Project is focused on the development, implementation and evaluation of Reduced Order Models (ROM) for application in the thermal analysis of complex engineering problems. Two basic approaches to developing a ROM for combined thermal conduction and enclosure radiation problems are considered. As a prerequisite to a ROM a fully coupled solution method for conduction/radiation models is required; a parallel implementation is explored for this class of problems. High-fidelity models of large, complex systems are now used routinely to verify design and performance. However, there are applications where the high-fidelity model is too large to be used repetitively in a design mode. One such application is the design of a control system that oversees the functioning of the complex, high-fidelity model. Examples include control systems for manufacturing processes such as brazing and annealing furnaces as well as control systems for the thermal management of optical systems. A reduced order model (ROM) seeks to reduce the number of degrees of freedom needed to represent the overall behavior of the large system without a significant loss in accuracy. The reduction in the number of degrees of freedom of the ROM leads to immediate increases in computational efficiency and allows many design parameters and perturbations to be quickly and effectively evaluated. Reduced order models are routinely used in solid mechanics where techniques such as modal analysis have reached a high state of refinement. Similar techniques have recently been applied in standard thermal conduction problems e.g. though the general use of ROM for heat transfer is not yet widespread. One major difficulty with the development of ROM for general thermal analysis is the need to include the very nonlinear effects of enclosure radiation in many applications. Many ROM methods have considered only linear or mildly nonlinear problems. In the present study a reduced order model is
Thermal Performance Testing of Order Dependancy of Aerogels Multilayered Insulation
Johnson, Wesley L.; Fesmire, James E.; Demko, J. A.
2009-01-01
Robust multilayer insulation systems have long been a goal of many research projects. Such insulation systems must provide some degree of structural support and also mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MU) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel and multilayer insulation systems have been tested at Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MU and aerogel blankets. Apparent thermal conductivity testing under cryogenic-vacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.
Bayesian model evidence for order selection and correlation testing.
Johnston, Leigh A; Mareels, Iven M Y; Egan, Gary F
2011-01-01
Model selection is a critical component of data analysis procedures, and is particularly difficult for small numbers of observations such as is typical of functional MRI datasets. In this paper we derive two Bayesian evidence-based model selection procedures that exploit the existence of an analytic form for the linear Gaussian model class. Firstly, an evidence information criterion is proposed as a model order selection procedure for auto-regressive models, outperforming the commonly employed Akaike and Bayesian information criteria in simulated data. Secondly, an evidence-based method for testing change in linear correlation between datasets is proposed, which is demonstrated to outperform both the traditional statistical test of the null hypothesis of no correlation change and the likelihood ratio test.
Observer based projective reduced-order synchronization of different chaotic systems
LI Guan-lin; CHEN Xi-you; LIU Feng-chun; MU Xian-min
2010-01-01
The projective reduced-order synchronization of two different chaotic systems with different orders is investigated based on the observer design in this paper.According to the observer theory,the reduced-order observer is designed.The projective synchronization can be realized by choosing the transition matrix of the observer as a diagonal matrix.Further,the synchronization between hyperchaotic Chen system(fourth order)and R(o)ssler system(third order)is taken as the example to demonstrate the effectiveness of the proposed observer.Numerical simulations confirm the effectiveness of the method.
Testing for one Generalized Linear Single Order Parameter
Ellegaard, Niels Langager; Christensen, Tage Emil; Dyre, Jeppe
work the order parameter may be chosen to have a non-exponential relaxation. The model predictions contradict the general consensus of the properties of viscous liquids in two ways: (i) The model predicts that following a linear isobaric temperature step, the normalized volume and entalpy relaxation...... functions are identical. This assumption conflicts with some (but not all) reports, utilizing the Tool-Narayanaswamy formalism to extrapolate from non-linear measurements to the linear regime. (ii) The model predicts that the theoretical "linear Prigogine-Defay" ratio is one. This ratio has never been...... responses or extrapolate from measurements of a glassy state away from equilibrium. Starting from a master equation description of inherent dynamics, we calculate the complex thermodynamic response functions. We device a way of testing for the generalized single order parameter model by measuring 3 complex...
Approximated Lax pairs for the reduced order integration of nonlinear evolution equations
Gerbeau, Jean-Frédéric; Lombardi, Damiano
2014-05-01
A reduced-order model algorithm, called ALP, is proposed to solve nonlinear evolution partial differential equations. It is based on approximations of generalized Lax pairs. Contrary to other reduced-order methods, like Proper Orthogonal Decomposition, the basis on which the solution is searched for evolves in time according to a dynamics specific to the problem. It is therefore well-suited to solving problems with progressive front or wave propagation. Another difference with other reduced-order methods is that it is not based on an off-line/on-line strategy. Numerical examples are shown for the linear advection, KdV and FKPP equations, in one and two dimensions.
Novel Reduced Order in Time Models for Problems in Nonlinear Aeroelasticity Project
National Aeronautics and Space Administration — Research is proposed for the development and implementation of state of the art, reduced order models for problems in nonlinear aeroelasticity. Highly efficient and...
Method reduces computer time for smoothing functions and derivatives through ninth order polynomials
Glauz, R. D.; Wilgus, C. A.
1969-01-01
Analysis presented is an efficient technique to adjust previously calculated orthogonal polynomial coefficients for an odd number of equally spaced data points. The adjusting technique derivation is for a ninth order polynomial. It reduces computer time for smoothing functions.
A REDUCED-ORDER MFE FORMULATION BASED ON POD METHOD FOR PARABOLIC EQUATIONS
Zhendong LUO; Lei LI; Ping SUN
2013-01-01
In this paper, we extend the applications of proper orthogonal decomposition (POD) method, i.e., apply POD method to a mixed finite element (MFE) formulation naturally satisfied Brezz-Babu˘ska for parabolic equations, establish a reduced-order MFE formulation with lower dimensions and suﬃciently high accuracy, and provide the error estimates between the reduced-order POD MFE solutions and the classical MFE solutions and the implementation of algorithm for solving reduced-order MFE formulation. Some numerical examples illustrate the fact that the results of numerical computation are consis-tent with theoretical conclusions. Moreover, it is shown that the new reduced-order MFE formulation based on POD method is feasible and eﬃcient for solving MFE formulation for parabolic equations.
Design of reduced-order state estimators for linear time-varying multivariable systems
Nguyen, Charles C.
1987-01-01
The design of reduced-order state estimators for linear time-varying multivariable systems is considered. Employing the concepts of matrix operators and the method of canonical transformations, this paper shows that there exists a reduced-order state estimator for linear time-varying systems that are 'lexicography-fixedly observable'. In addition, the eigenvalues of the estimator can be arbitrarily assigned. A simple algorithm is proposed for the design of the state estimator.
Investigation of the Stability of POD-Galerkin Techniques for Reduced Order Model Development
2016-01-09
CFD solutions comparison of Case A at x/L = 0.5 for cases in Table 4. 12 The remaining three cases with multiple frequencies in the forcing function...Techniques for Reduced Order Model Development 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Huang, C...mitigate the stability issues encountered in developing a reduced order model (ROM) for combustion response to specified excitations using the Euler
Reduced-order modeling for cardiac electrophysiology. Application to parameter identification
Boulakia, Muriel; Gerbeau, Jean-Frédéric
2011-01-01
A reduced-order model based on Proper Orthogonal Decomposition (POD) is proposed for the bidomain equations of cardiac electrophysiology. Its accuracy is assessed through electrocardiograms in various configurations, including myocardium infarctions and long-time simulations. We show in particular that a restitution curve can efficiently be approximated by this approach. The reduced-order model is then used in an inverse problem solved by an evolutionary algorithm. Some attempts are presented to identify ionic parameters and infarction locations from synthetic ECGs.
A new reduced-order observer design for the synchronization of Lorenz systems
Martinez-Guerra, R. [Departamento de Control Automatico, CINVESTAV-IPN, AP 14-740, CP 07360, Mexico, DF (Mexico)] e-mail: rguerra@ctrl.cinvestav.mx; Cruz-Victoria, J.C. [Departamento de Control Automatico, CINVESTAV-IPN, AP 14-740, CP 07360, Mexico, DF (Mexico); Gonzalez-Galan, R. [Departamento de Control Automatico, CINVESTAV-IPN, AP 14-740, CP 07360, Mexico, DF (Mexico); Aguilar-Lopez, R. [Departamento de Energia, UAM-Azcapotzalco, 02200 (Mexico)
2006-04-01
In this paper we tackle the synchronization of Lorenz system problem using a new proportional reduced-order observer design in the algebraic and differential setting. We prove the asymptotic stability of the resulting error system and by means of algebraic manipulations we obtain the estimates of the current states (master system), the construction of a proportional reduced-order observer is the main ingredient in our approach. Finally, we present a simulation to illustrate the effectiveness of the suggested approach.
van der Linden, Willem J.
1995-01-01
Dichotomous item response theory (IRT) models can be viewed as families of stochastically ordered distributions of responses to test items. This paper explores several properties of such distributiom. The focus is on the conditions under which stochastic order in families of conditional distribution
A reduced-rank approach for implementing higher-order Volterra filters
O. Batista, Eduardo L.; Seara, Rui
2016-12-01
The use of Volterra filters in practical applications is often limited by their high computational burden. To cope with this problem, many strategies for implementing Volterra filters with reduced complexity have been proposed in the open literature. Some of these strategies are based on reduced-rank approaches obtained by defining a matrix of filter coefficients and applying the singular value decomposition to such a matrix. Then, discarding the smaller singular values, effective reduced-complexity Volterra implementations can be obtained. The application of this type of approach to higher-order Volterra filters (considering orders greater than 2) is however not straightforward, which is especially due to some difficulties encountered in the definition of higher-order coefficient matrices. In this context, the present paper is devoted to the development of a novel reduced-rank approach for implementing higher-order Volterra filters. Such an approach is based on a new form of Volterra kernel implementation that allows decomposing higher-order kernels into structures composed only of second-order kernels. Then, applying the singular value decomposition to the coefficient matrices of these second-order kernels, effective implementations for higher-order Volterra filters can be obtained. Simulation results are presented aiming to assess the effectiveness of the proposed approach.
Variable-fidelity and reduced-order models for aero data for loads predictions
Goertz, Stefan; Zimmermann, Ralf; Han, Zhong Hua
2013-01-01
This paper summarizes recent progress in developing metamodels for efficiently predicting the aerodynamic loads acting on industrial aircraft configurations. We introduce a physics-based approach to reduced-order modeling based on proper orthogonal decomposition of snapshots of the full-order CFD...
UDU factored Lyapunov recursions solve optimal reduced-order LQG problems
Willigenburg, van L.G.; Koning, de W.L.
2004-01-01
A new algorithm is presented to solve both the finite-horizon time-varying and infinite-horizon time-invariant discrete-time optimal reduced-order LQG problem. In both cases the first order necessary optimality conditions can be represented by two non-linearly coupled discrete-time Lyapunov equation
A Reduced-Order Model for Evaluating the Dynamic Response of Multilayer Plates to Impulsive Loads
2016-04-12
distribution is unlimited SAE INTERNATIONAL • Motivation • Technical Approach • Reduced Order Model (ROM) • Validation – by Spectrum Finite Element ...also be paramount factors for Army vehicles in order for faster transport, greater fuel conservation, higher payload and higher mobility. • Develop...Matrix • The departure wave vectors ?̃?∗ and ?̃? contain same elements but in different order. It can be expressed in equivalence through a global
Bootstrap and second-order tests of risk difference.
Lloyd, Chris J
2010-09-01
Clinical trials data often come in the form of low-dimensional tables of small counts. Standard approximate tests such as score and likelihood ratio tests are imperfect in several respects. First, they can give quite different answers from the same data. Second, the actual type-1 error can differ significantly from nominal, even for quite large sample sizes. Third, exact inferences based on these can be strongly nonmonotonic functions of the null parameter and lead to confidence sets that are discontiguous. There are two modern approaches to small sample inference. One is to use so-called higher order asymptotics (Reid, 2003, Annal of Statistics 31, 1695-1731) to provide an explicit adjustment to the likelihood ratio statistic. The theory for this is complex but the statistic is quick to compute. The second approach is to perform an exact calculation of significance assuming the nuisance parameters equal their null estimate (Lee and Young, 2005, Statistic and Probability Letters 71, 143-153), which is a kind of parametric bootstrap. The purpose of this article is to explain and evaluate these two methods, for testing whether a difference in probabilities p(2) - p(1) exceeds a prechosen noninferiority margin δ(0) . On the basis of an extensive numerical study, we recommend bootstrap P-values as superior to all other alternatives. First, they produce practically identical answers regardless of the basic test statistic chosen. Second, they have excellent size accuracy and higher power. Third, they vary much less erratically with the null parameter value δ(0) . © 2009, The International Biometric Society.
A Highest Order Hypothesis Compatibility Test for Monocular SLAM
Edmundo Guerra
2013-08-01
Full Text Available Simultaneous Location and Mapping (SLAM is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hypothesis Compatibility Test, HOHCT. The Delayed Inverse-Depth technique is used to initialize new features in the system and defines a single hypothesis for the initial depth of features with the use of a stochastic technique of triangulation. The introduced HOHCT method is based on the evaluation of statistically compatible hypotheses and a search algorithm designed to exploit the strengths of the Delayed Inverse- Depth technique to achieve good performance results. This work presents the HOHCT with a detailed formulation of the monocular DI-D SLAM problem. The performance of the proposed HOHCT is validated with experimental results, in both indoor and outdoor environments, while its costs are compared with other popular approaches.
A Highest Order Hypothesis Compatibility Test for Monocular SLAM
Edmundo Guerra
2013-08-01
Full Text Available Simultaneous Location and Mapping (SLAM is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hypothesis Compatibility Test, HOHCT. The Delayed Inverse-Depth technique is used to initialize new features in the system and defines a single hypothesis for the initial depth of features with the use of a stochastic technique of triangulation. The introduced HOHCT method is based on the evaluation of statistically compatible hypotheses and a search algorithm designed to exploit the strengths of the Delayed Inverse-Depth technique to achieve good performance results. This work presents the HOHCT with a detailed formulation of the monocular DI-D SLAM problem. The performance of the proposed HOHCT is validated with experimental results, in both indoor and outdoor environments, while its costs are compared with other popular approaches.
A test of first order scaling in Nf=2 QCD
Cossu, G; Di Giacomo, A; Pica, C
2007-01-01
We complete our analysis of Nf=2 QCD based on the lattice staggered fermion formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one is able to test the universality class with given critical exponent yh. This strategy has been used to test the O(4) universality class and it has been presented at the previous Lattice conferences. No agreement was found with simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up to 32 and Lt=4. With the same strategy, we now investigate the possibility of a first order transition using a new set of Monte Carlo data corresponding to yh=3 in the same mass and volume range as the one used for O(4). A substantial agreement is observed both in the specific heat scaling and in the scaling of the chiral condensate, while the chiral susceptibilities still presents visible deviation from scaling in the mass range explored.
Reduced density matrices and topological order in a quantum dimer model
Furukawa, Shunsuke [Laboratoire de Physique Theorique de la Matiere Condensee, UMR 7600 of CNRS, Universite P et M Curie, case 121, 4 Place Jussieu, 75252 Paris Cedex (France); Misguich, Gregoire [Service de Physique Theorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Oshikawa, Masaki [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581 (Japan)
2007-04-11
Resonating valence bond (RVB) liquids in two dimensions are believed to exhibit topological order and to admit no local order parameter of any kind. This is a defining property of 'liquids', but it has been confirmed explicitly only in a few exactly solvable models. In this paper, we investigate the quantum dimer model on the triangular lattice. This possesses an RVB-type liquid phase, however, for which the absence of a local order parameter has not been proved. We examine the question numerically with a measure based on reduced density matrices. We find a scaling of the measure which strongly supports the absence of any local order parameter.
Reduced-Order Modeling of Parametrically Excited Micro-Electro-Mechanical Systems (MEMS
Sangram Redkar
2010-01-01
Full Text Available Reduced-order modeling is a systematic way of constructing models with smaller number of states that can capture the “essential dynamics” of the large-scale systems, accurately. In this paper, reduced-order modeling and control techniques for parametrically excited MEMS are presented. The techniques proposed here use the Lyapunov-Floquet (L-F transformation that makes the linear part of transformed equations time invariant. In this work, three model reduction techniques for MEMS are suggested. First method is simply an application of the well-known Guyan-like reduction method to nonlinear systems. The second technique is based on singular perturbation, where the transformed system dynamics is partitioned as fast and slow dynamics and the system of differential equations is converted into a differential algebraic (DAE system. In the third technique, the concept of invariant manifold for time-periodic systems is used. The “time periodic invariant manifold” based technique yields “reducibility conditions”. This is an important result because it helps us to understand the various types of resonances present in the system. These resonances indicate a tight coupling between the system states, and in order to retain the dynamic characteristics, one has to preserve all these “resonant” states in the reduced-order model. Thus, if the “reducibility conditions” are satisfied, only then a nonlinear order reduction based on invariant manifold approach is possible. It is found that the invariant manifold approach yields the most accurate results followed by the nonlinear projection and linear technique. These methodologies are general, free from small parameter assumptions, and can be applied to a variety of MEM systems like resonators, sensors and filters. The reduced-order models can be used for parametric study, sensitivity analysis and/or controller design. The controller design is based on the reduced-order system. Thus, first the
Wind Farm Flow Modeling using an Input-Output Reduced-Order Model
Annoni, Jennifer; Gebraad, Pieter; Seiler, Peter
2016-08-01
Wind turbines in a wind farm operate individually to maximize their own power regardless of the impact of aerodynamic interactions on neighboring turbines. There is the potential to increase power and reduce overall structural loads by properly coordinating turbines. To perform control design and analysis, a model needs to be of low computational cost, but retains the necessary dynamics seen in high-fidelity models. The objective of this work is to obtain a reduced-order model that represents the full-order flow computed using a high-fidelity model. A variety of methods, including proper orthogonal decomposition and dynamic mode decomposition, can be used to extract the dominant flow structures and obtain a reduced-order model. In this paper, we combine proper orthogonal decomposition with a system identification technique to produce an input-output reduced-order model. This technique is used to construct a reduced-order model of the flow within a two-turbine array computed using a large-eddy simulation.
Experiences of the REACH testing proposals system to reduce animal testing.
Taylor, Katy; Stengel, Wolfgang; Casalegno, Carlotta; Andrew, David
2014-01-01
In order to reduce animal testing, companies registering chemical substances under the EU REACH legislation must propose rather than conduct certain tests on animals. Third parties can submit 'scientifically valid information' relevant to these proposals to the Agency responsible, the European Chemicals Agency (ECHA), who are obliged to take the information into account. The European Coalition to End Animal Experiments (ECEAE) provided comments on nearly half of the 817 proposals for vertebrate tests on 480 substances published for comment for the first REACH deadline (between 1 August 2009 and 31 July 2012). The paper summarises the response by registrants and the Agency to third party comments and highlights issues with the use of read across, in vitro tests, QSAR and weight of evidence approaches. Use of existing data and evidence that testing is legally or scientifically unjustified remain the most successful comments for third parties to submit. There is a worrying conservatism within the Agency regarding the acceptance of alternative approaches and examples of where registrants have also failed to maximise opportunities to avoid testing.
Martins, Carlos Manuel Silva; da Costa Teixeira, Andreia Sofia; de Azevedo, Luís Filipe Ribeiro; Sá, Luísa Maria Barbosa; Santos, Paulo Alexandre Azevedo Pereira; do Couto, Maria Luciana Gomes Domingues; da Costa Pereira, Altamiro Manuel Rodrigues; Hespanhol, Alberto Augusto Oliveira Pinto; da Costa Santos, Cristina Maria Nogueira
2017-02-20
impact and reduced unnecessary prescription of tests. The fact that it was not possible to perform the randomization at the family physicians' level, but only of the computer servers is a limitation of our study. Future research should assess the impact of different tests ordering systems during longer periods. ISRCTN45427977 , May 1(st) 2014 (retrospectively registered).
Yan Zhang
2013-01-01
Full Text Available We discuss linear multiagent systems consensus problem with distributed reduced-order observer-based protocol under switching topology. We use Jordan decomposition method to prove that the proposed protocols can solve consensus problem under directed fixed topology. By constructing a parameter-dependent common Lyapunov function, we prove that the distributed reduced-order observer-based protocol can also solve the continuous-time multi-agent consensus problem under the undirected switching interconnection topology. Then, we investigate the leader-following consensus problem and propose a reduced-order observer-based protocol for each following agent. By using similar analysis method, we can prove that all following agents can track the leader under a class of directed interaction topologies. Finally, the given simulation example also shows the effectiveness of our obtained result.
Reduced order variational multiscale enrichment method for thermo-mechanical problems
Zhang, Shuhai; Oskay, Caglar
2017-06-01
This manuscript presents the formulation and implementation of the reduced order variational multiscale enrichment (ROVME) method for thermo-mechanical problems. ROVME is extended to model the inelastic behavior of heterogeneous structures, in which the constituent properties are temperature sensitive. The temperature-dependent coefficient tensors of the reduced order method are approximated in an efficient manner, retaining the computational efficiency of the reduced order model in the presence of spatial/temporal temperature variations. A Newton-Raphson iterative scheme is formulated and implemented for the numerical evaluation of nonlinear system of equations associated with the proposed ROVME method. Numerical verifications are performed to assess the efficiency and accuracy of the proposed computational framework. The results of the verifications reveal that ROVME retains reasonable accuracy and achieves high efficiency in the presence of hermo-mechanical loads.
A Reduced-Order Model of Transport Phenomena for Power Plant Simulation
Paul Cizmas; Brian Richardson; Thomas Brenner; Raymond Fontenot
2009-09-30
A reduced-order model based on proper orthogonal decomposition (POD) has been developed to simulate transient two- and three-dimensional isothermal and non-isothermal flows in a fluidized bed. Reduced-order models of void fraction, gas and solids temperatures, granular energy, and z-direction gas and solids velocity have been added to the previous version of the code. These algorithms are presented and their implementation is discussed. Verification studies are presented for each algorithm. A number of methods to accelerate the computations performed by the reduced-order model are presented. The errors associated with each acceleration method are computed and discussed. Using a combination of acceleration methods, a two-dimensional isothermal simulation using the reduced-order model is shown to be 114 times faster than using the full-order model. In the pursue of achieving the objectives of the project and completing the tasks planned for this program, several unplanned and unforeseen results, methods and studies have been generated. These additional accomplishments are also presented and they include: (1) a study of the effect of snapshot sampling time on the computation of the POD basis functions, (2) an investigation of different strategies for generating the autocorrelation matrix used to find the POD basis functions, (3) the development and implementation of a bubble detection and tracking algorithm based on mathematical morphology, (4) a method for augmenting the proper orthogonal decomposition to better capture flows with discontinuities, such as bubbles, and (5) a mixed reduced-order/full-order model, called point-mode proper orthogonal decomposition, designed to avoid unphysical due to approximation errors. The limitations of the proper orthogonal decomposition method in simulating transient flows with moving discontinuities, such as bubbling flows, are discussed and several methods are proposed to adapt the method for future use.
Reduced enrichment for research and test reactors: Proceedings
1993-07-01
The 15th annual Reduced Enrichment for Research and Test Reactors (RERTR) international meeting was organized by Ris{o} National Laboratory in cooperation with the International Atomic Energy Agency and Argonne National Laboratory. The topics of the meeting were the following: National Programs, Fuel Fabrication, Licensing Aspects, States of Conversion, Fuel Testing, and Fuel Cycle. Individual papers have been cataloged separately.
An improved method using factor division algorithm for reducing the order of linear dynamical system
SHARAD KUMAR TIWARI; GAGANDEEP KAUR
2016-06-01
An improved method is proposed to determine the reduced order model of large scale linear time invariant system. The dominant poles of the low order system are calculated by clustering method. The selection of pole to the cluster point is based on the contributions of each pole in redefining time moment and redefiningMarkov parameters. The coefficients of the numerator polynomial for reduced model are obtained using a factor division algorithm. This method is computationally efficient and keeps up the stability and input output characteristic of the original arrangement
Reduced-order models for dynamic control of power plants based on controllability and observability
Ahmed, G.S.; Abdel-Magid, Y.L.
1987-07-01
A new technique for constructing dynamic equivalents of power systems is developed. The method identifies the important modes of the system utilizing a performance index based on the notions of controllability and observability. The system state variables corresponding to the retained modes are identified by inspection of the elements of the sensitivity matrix relating the eigenvalues to the state variables. The suitability of the method for obtaining reduced-order models of power systems for dynamic-control purposes is demonstrated on a single-machine infinite-bus system. Several reduced-order models are produced and their accuracy discussed. 11 refs.
Vidyarthi, Arpana R; Hamill, Timothy; Green, Adrienne L; Rosenbluth, Glenn; Baron, Robert B
2015-01-01
Hospital laboratory test volume is increasing, and overutilization contributes to errors and costs. Efforts to reduce laboratory utilization have targeted aspects of ordering behavior, but few have utilized a multilevel collaborative approach. The study team partnered with residents to reduce unnecessary laboratory tests and associated costs through multilevel interventions across the academic medical center. The study team selected laboratory tests for intervention based on cost, volume, and ordering frequency (complete blood count [CBC] and CBC with differential, common electrolytes, blood enzymes, and liver function tests). Interventions were designed collaboratively with residents and targeted components of ordering behavior, including system changes, teaching, social marketing, academic detailing, financial incentives, and audit/feedback. Laboratory ordering was reduced by 8% cumulatively over 3 years, saving $2 019 000. By involving residents at every stage of the intervention and targeting multiple levels simultaneously, laboratory utilization was reduced and cost savings were sustained over 3 years. © 2014 by the American College of Medical Quality.
Energy balance and mass conservation in reduced order models of fluid flows
Mohebujjaman, Muhammad; Rebholz, Leo G.; Xie, Xuping; Iliescu, Traian
2017-10-01
In this paper, we investigate theoretically and computationally the conservation properties of reduced order models (ROMs) for fluid flows. Specifically, we investigate whether the ROMs satisfy the same (or similar) energy balance and mass conservation as those satisfied by the Navier-Stokes equations. All of our theoretical findings are illustrated and tested in numerical simulations of a 2D flow past a circular cylinder at a Reynolds number Re = 100. First, we investigate the ROM energy balance. We show that using the snapshot average for the centering trajectory (which is a popular treatment of nonhomogeneous boundary conditions in ROMs) yields an incorrect energy balance. Then, we propose a new approach, in which we replace the snapshot average with the Stokes extension. Theoretically, the Stokes extension produces an accurate energy balance. Numerically, the Stokes extension yields more accurate results than the standard snapshot average, especially for longer time intervals. Our second contribution centers around ROM mass conservation. We consider ROMs created using two types of finite elements: the standard Taylor-Hood (TH) element, which satisfies the mass conservation weakly, and the Scott-Vogelius (SV) element, which satisfies the mass conservation pointwise. Theoretically, the error estimates for the SV-ROM are sharper than those for the TH-ROM. Numerically, the SV-ROM yields significantly more accurate results, especially for coarser meshes and longer time intervals.
A reduced-order, single-bubble cavitation model with applications to therapeutic ultrasound.
Kreider, Wayne; Crum, Lawrence A; Bailey, Michael R; Sapozhnikov, Oleg A
2011-11-01
Cavitation often occurs in therapeutic applications of medical ultrasound such as shock-wave lithotripsy (SWL) and high-intensity focused ultrasound (HIFU). Because cavitation bubbles can affect an intended treatment, it is important to understand the dynamics of bubbles in this context. The relevant context includes very high acoustic pressures and frequencies as well as elevated temperatures. Relative to much of the prior research on cavitation and bubble dynamics, such conditions are unique. To address the relevant physics, a reduced-order model of a single, spherical bubble is proposed that incorporates phase change at the liquid-gas interface as well as heat and mass transport in both phases. Based on the energy lost during the inertial collapse and rebound of a millimeter-sized bubble, experimental observations were used to tune and test model predictions. In addition, benchmarks from the published literature were used to assess various aspects of model performance. Benchmark comparisons demonstrate that the model captures the basic physics of phase change and diffusive transport, while it is quantitatively sensitive to specific model assumptions and implementation details. Given its performance and numerical stability, the model can be used to explore bubble behaviors across a broad parameter space relevant to therapeutic ultrasound.
Chen Xin
2015-10-01
Full Text Available Aerothermoelasticity is one of the key technologies for hypersonic vehicles. Accurate and efficient computation of the aerothermodynamics is one of the primary challenges for hypersonic aerothermoelastic analysis. Aimed at solving the shortcomings of engineering calculation, computation fluid dynamics (CFD and experimental investigation, a reduced order modeling (ROM framework for aerothermodynamics based on CFD predictions using an enhanced algorithm of fast maximin Latin hypercube design is developed. Both proper orthogonal decomposition (POD and surrogate are considered and compared to construct ROMs. Two surrogate approaches named Kriging and optimized radial basis function (ORBF are utilized to construct ROMs. Furthermore, an enhanced algorithm of fast maximin Latin hypercube design is proposed, which proves to be helpful to improve the precisions of ROMs. Test results for the three-dimensional aerothermodynamic over a hypersonic surface indicate that: the ROMs precision based on Kriging is better than that by ORBF, ROMs based on Kriging are marginally more accurate than ROMs based on POD-Kriging. In a word, the ROM framework for hypersonic aerothermodynamics has good precision and efficiency.
Chen X in; Liu Li; Long Teng; Yue Zhenjiang
2015-01-01
Aerothermoelasticity is one of the key technologies for hypersonic vehicles. Accurate and efficient computation of the aerothermodynamics is one of the primary challenges for hypersonic aerothermoelastic analysis. Aimed at solving the shortcomings of engineering calculation, compu-tation fluid dynamics (CFD) and experimental investigation, a reduced order modeling (ROM) framework for aerothermodynamics based on CFD predictions using an enhanced algorithm of fast maximin Latin hypercube design is developed. Both proper orthogonal decomposition (POD) and surrogate are considered and compared to construct ROMs. Two surrogate approaches named Kriging and optimized radial basis function (ORBF) are utilized to construct ROMs. Furthermore, an enhanced algorithm of fast maximin Latin hypercube design is proposed, which proves to be helpful to improve the precisions of ROMs. Test results for the three-dimensional aerothermody-namic over a hypersonic surface indicate that:the ROMs precision based on Kriging is better than that by ORBF, ROMs based on Kriging are marginally more accurate than ROMs based on POD-Kriging. In a word, the ROM framework for hypersonic aerothermodynamics has good precision and efficiency.
2013-12-27
... annual stress tests to determine whether the companies have the capital necessary to absorb losses as a... amended Summary Instructions and Guidance relating to the performance of stress tests as of September 30... AGENCY 12 CFR Part 1238 Orders: Supplemental Orders on Reporting by Regulated Entities of Stress...
Reducing unnecessary lab testing in the ICU with artificial intelligence.
Cismondi, F; Celi, L A; Fialho, A S; Vieira, S M; Reti, S R; Sousa, J M C; Finkelstein, S N
2013-05-01
To reduce unnecessary lab testing by predicting when a proposed future lab test is likely to contribute information gain and thereby influence clinical management in patients with gastrointestinal bleeding. Recent studies have demonstrated that frequent laboratory testing does not necessarily relate to better outcomes. Data preprocessing, feature selection, and classification were performed and an artificial intelligence tool, fuzzy modeling, was used to identify lab tests that do not contribute an information gain. There were 11 input variables in total. Ten of these were derived from bedside monitor trends heart rate, oxygen saturation, respiratory rate, temperature, blood pressure, and urine collections, as well as infusion products and transfusions. The final input variable was a previous value from one of the eight lab tests being predicted: calcium, PTT, hematocrit, fibrinogen, lactate, platelets, INR and hemoglobin. The outcome for each test was a binary framework defining whether a test result contributed information gain or not. Predictive modeling was applied to recognize unnecessary lab tests in a real world ICU database extract comprising 746 patients with gastrointestinal bleeding. Classification accuracy of necessary and unnecessary lab tests of greater than 80% was achieved for all eight lab tests. Sensitivity and specificity were satisfactory for all the outcomes. An average reduction of 50% of the lab tests was obtained. This is an improvement from previously reported similar studies with average performance 37% by [1-3]. Reducing frequent lab testing and the potential clinical and financial implications are an important issue in intensive care. In this work we present an artificial intelligence method to predict the benefit of proposed future laboratory tests. Using ICU data from 746 patients with gastrointestinal bleeding, and eleven measurements, we demonstrate high accuracy in predicting the likely information to be gained from proposed future
A Reduced-Order Model for Structural Wave Control and the Concept of Degree of Controllability
王泉; 王大钧; 苏先樾
1994-01-01
This paper introduces the concept and criteria of controllability and degree of controllability for structural wave control, and advances a new approach to structural reduced-order model, which is similar to the constrained substructural method in dynamics, and is also the extension of the method of aggregation raised by Aoki. It has physical meaning and is easy to realize.
Raghupathy, Arun; Ghia, Karman; Ghia, Urmila
2008-11-01
Compact Thermal Models (CTM) to represent IC packages has been traditionally developed using the DELPHI-based (DEvelopment of Libraries of PHysical models for an Integrated design) methodology. The drawbacks of this method are presented, and an alternative method is proposed. A reduced-order model that provides the complete thermal information accurately with less computational resources can be effectively used in system level simulations. Proper Orthogonal Decomposition (POD), a statistical method, can be used to reduce the order of the degree of freedom or variables of the computations for such a problem. POD along with the Galerkin projection allows us to create reduced-order models that reproduce the characteristics of the system with a considerable reduction in computational resources while maintaining a high level of accuracy. The goal of this work is to show that this method can be applied to obtain a boundary condition independent reduced-order thermal model for complex components. The methodology is applied to the 1D transient heat equation.
Approaches for Reduced Order Modeling of Electrically Actuated von Karman Microplates
Saghir, Shahid
2016-07-25
This article presents and compares different approaches to develop reduced order models for the nonlinear von Karman rectangular microplates actuated by nonlinear electrostatic forces. The reduced-order models aim to investigate the static and dynamic behavior of the plate under small and large actuation forces. A fully clamped microplate is considered. Different types of basis functions are used in conjunction with the Galerkin method to discretize the governing equations. First we investigate the convergence with the number of modes retained in the model. Then for validation purpose, a comparison of the static results is made with the results calculated by a nonlinear finite element model. The linear eigenvalue problem for the plate under the electrostatic force is solved for a wide range of voltages up to pull-in. Results among the various reduced-order modes are compared and are also validated by comparing to results of the finite-element model. Further, the reduced order models are employed to capture the forced dynamic response of the microplate under small and large vibration amplitudes. Comparison of the different approaches are made for this case. Keywords: electrically actuated microplates, static analysis, dynamics of microplates, diaphragm vibration, large amplitude vibrations, nonlinear dynamics
Performance of a reduced-order FSI model for flow-induced vocal fold vibration
Chang, Siyuan; Luo, Haoxiang; Luo's lab Team
2016-11-01
Vocal fold vibration during speech production involves a three-dimensional unsteady glottal jet flow and three-dimensional nonlinear tissue mechanics. A full 3D fluid-structure interaction (FSI) model is computationally expensive even though it provides most accurate information about the system. On the other hand, an efficient reduced-order FSI model is useful for fast simulation and analysis of the vocal fold dynamics, which is often needed in procedures such as optimization and parameter estimation. In this work, we study the performance of a reduced-order model as compared with the corresponding full 3D model in terms of its accuracy in predicting the vibration frequency and deformation mode. In the reduced-order model, we use a 1D flow model coupled with a 3D tissue model. Two different hyperelastic tissue behaviors are assumed. In addition, the vocal fold thickness and subglottal pressure are varied for systematic comparison. The result shows that the reduced-order model provides consistent predictions as the full 3D model across different tissue material assumptions and subglottal pressures. However, the vocal fold thickness has most effect on the model accuracy, especially when the vocal fold is thin. Supported by the NSF.
An LMI-based unified approach to reduced-order controller design
郭雷; 忻欣; 冯纯伯
1997-01-01
The design of reduced-order controllers is considered for stabilization control, covariance upper bound control, linear quadratic regulator, ∞ control, H∞ control, positive real control problems and robust H2 control, robust ∞ control and robust H∞ control problems for generalized linear plants without any additional assumptions. An upper bound of the order is obtained with which the (robust) controllers can guarantee stability constraints and satisfy the same design objectives as the so-called "full-order" controllers. A unified linear-matrix-inequality ( LMI) based approach to reduced-order (robust) controller design for all the above-mentioned problems is provided. It us shown that each of these problems is solvable if and only if two uncoupled LMIs with an LMI-type constraint have a pair of positive definite solutions, one of which has a lower dimension than that given by Skelton and iwasaki (1995). All desired reduced-order (robust) controllers are parameterized via the solutions of LMIs Moreov
An Online Method for Interpolating Linear Parametric Reduced-Order Models
Amsallem, David
2011-01-01
A two-step online method is proposed for interpolating projection-based linear parametric reduced-order models (ROMs) in order to construct a new ROM for a new set of parameter values. The first step of this method transforms each precomputed ROM into a consistent set of generalized coordinates. The second step interpolates the associated linear operators on their appropriate matrix manifold. Real-time performance is achieved by precomputing inner products between the reduced-order bases underlying the precomputed ROMs. The proposed method is illustrated by applications in mechanical and aeronautical engineering. In particular, its robustness is demonstrated by its ability to handle the case where the sampled parameter set values exhibit a mode veering phenomenon. © 2011 Society for Industrial and Applied Mathematics.
Bhattacharjee, Satyaki; Matouš, Karel
2016-05-01
A new manifold-based reduced order model for nonlinear problems in multiscale modeling of heterogeneous hyperelastic materials is presented. The model relies on a global geometric framework for nonlinear dimensionality reduction (Isomap), and the macroscopic loading parameters are linked to the reduced space using a Neural Network. The proposed model provides both homogenization and localization of the multiscale solution in the context of computational homogenization. To construct the manifold, we perform a number of large three-dimensional simulations of a statistically representative unit cell using a parallel finite strain finite element solver. The manifold-based reduced order model is verified using common principles from the machine-learning community. Both homogenization and localization of the multiscale solution are demonstrated on a large three-dimensional example and the local microscopic fields as well as the homogenized macroscopic potential are obtained with acceptable engineering accuracy.
Efficacy test of a toothpaste in reducing extrinsic dental stain
Agustanti, A.; Ramadhani, S. A.; Adiatman, M.; Rahardjo, A.; Callea, M.; Yavuz, I.; Maharani, D. A.
2017-08-01
This clinical trial compared the external dental stain reduction achieved by tested toothpaste versus placebo in adult patients. In this double-blind, parallel, randomised clinical trial, 45 female volunteers with a mean age of 20 years old were included. All study subjects front teeth were topically applicated with Silver Diamine Fluoride (SDF) to create external dental stains. Subjects were randomized into test (n=22) and control (n=23) groups. Toothpastes were used for two days to analyse the effects of removing external stains on the labial surfaces of all anterior teeth. VITA Easyshade Advance 4.0 was used to measure dental extrinsic stains changes. The analysis showed statistically significant efficacy of the tested toothpaste in reducing external dental stain caused by SDF, comparing to the placebo toothpaste, after one and two days of usage. The tested toothpaste was effective in reducing dental stain.
A reduced-form model for level-1 limit order books
2015-01-01
One popular approach to model the limit order books dynamics of the best bid and ask at level-1 is to use the reduced-form diffusion approximations. It is well known that the biggest contributing factor to the price movement is the imbalance of the best bid and ask. We investigate the data of the level-1 limit order books of a basket of stocks and study the numerical evidence of drift, correlation, volatility and their dependence on the imbalance. Based on the numerical discoveries, we develo...
Reduced order generalized integrators with phase compensation for three-phase active power filter
Xie, Chuan; Li, Kai; Zhao, Xin
2017-01-01
Current regulation is a critical issue for the stable operation of three-phase active power filters (APF). The challenge of the current controller lies in how to track the high slew rate reference with zero steady-state error in a fast and accurate way. Conventionally, multiple paralleled second-order...... generalized integrators (SOGIs) are utilized to achieve those objectives. However, it will increase the computational burden due to calculation of the multiple paralleled SOGIs. To overcome this issue, phase compensated reduced order generalized integrator (ROGI) is proposed in this paper. Compared...
Interpolation-based reduced-order modelling for steady transonic flows via manifold learning
Franz, Thomas; Zimmermann, Ralf; Goertz, Stefan
2014-01-01
This paper presents a parametric reduced-order model (ROM) based on manifold learning (ML) for use in steady transonic aerodynamic applications. The main objective of this work is to derive an efficient ROM that exploits the low-dimensional nonlinear solution manifold to ensure an improved...... that has the ability to predict approximate CFD solutions at untried parameter combinations, Isomap is coupled with an interpolation method to capture the variations in parameters like the angle of attack or the Mach number. Furthermore, an approximate local inverse mapping from the reduced...
Qi, Di; Majda, Andrew J.
2017-03-01
A low-dimensional reduced-order statistical closure model is developed for quantifying the uncertainty to changes in forcing in a barotropic turbulent system with topography involving interactions between small-scale motions and a large-scale mean flow. Imperfect model sensitivity is improved through a recent mathematical strategy for calibrating model errors in a training phase, where information theory and linear statistical response theory are combined in a systematic fashion to achieve the optimal model parameters. Statistical theories about a Gaussian invariant measure and the exact statistical energy equations are also developed for the truncated barotropic equations that can be used to improve the imperfect model prediction skill. A stringent paradigm model of 57 degrees of freedom is used to display the feasibility of the reduced-order methods. This simple model creates large-scale zonal mean flow shifting directions from westward to eastward jets with an abrupt change in amplitude when perturbations are applied, and prototype blocked and unblocked patterns can be generated in this simple model similar to the real natural system. Principal statistical responses in mean and variance can be captured by the reduced-order models with desirable accuracy and efficiency with only 3 resolved modes. An even more challenging regime with non-Gaussian equilibrium statistics using the fluctuation equations is also tested in the reduced-order models with accurate prediction using the first 5 resolved modes. These reduced-order models also show potential for uncertainty quantification and prediction in more complex realistic geophysical turbulent dynamical systems.
Inappropriate emergency laboratory test ordering: defensive or peer evidence shared based medicine?
C. Descovich
2013-05-01
Full Text Available BACKGROUND The laboratory overuse is widely prevalent in hospital practice, mostly in the emergency care. Reasons for excessive and inappropriate test-ordering include defensive behaviour and fear or uncertainty, lack of experience, the misuse of protocols and guidelines, “routine” and local attitudes, inadequate educational feedback and clinician’s unawareness about the cost of examinations and their related implications. AIM OF THE STUDY AND METHODS The primary target of our working group was to reduce inappropriate ordering on a urgent basis test, implementing further examinations not yet previewed in the hospital panel of the available urgencies, according to the evidence based diagnosis concept. The secondary goal was to indicate strategies of re-engineering of the processes, improving turnaround time in the laboratory management of emergencies. After evaluating, as first intervention, the more reliable sources for practice guidelines, systematic reviews and RCTs, the committee further discussed main topics with in-hospital stakeholders, selected from Emergency, Internal Medicine and Surgery Depts. The working group, in many subsequent audits, tried to obtain a systematic feed back with all involved professionals. RESULTS After reviewing literature’s evidence, the board constrained testing options by defining the basic emergency laboratory panel tests (blood type, hemogram, blood urea nitrogen, plasma creatinine, glucose, sodium, potassium, chloride, osmolarity, CRP, bicarbonate, CPK, creatine phosphokinase-MB, myoglobin, troponin, BNP and NT-proBNP, PT-INR, PTT, D-dimer, beta- HCG, biochemical urinalysis etc.. As final result, the proposed tests reduced the overall number of inappropriate investigations and increased, with newer and updated tests, the available panel for critical patients. DISCUSSION A collegiate review of data reporting, in-hospital deepening of problems and the inter- professional discussion of the evidences
Arshad, Muhammad; Lu, Dianchen; Wang, Jun
2017-07-01
In this paper, we pursue the general form of the fractional reduced differential transform method (DTM) to (N+1)-dimensional case, so that fractional order partial differential equations (PDEs) can be resolved effectively. The most distinct aspect of this method is that no prescribed assumptions are required, and the huge computational exertion is reduced and round-off errors are also evaded. We utilize the proposed scheme on some initial value problems and approximate numerical solutions of linear and nonlinear time fractional PDEs are obtained, which shows that the method is highly accurate and simple to apply. The proposed technique is thus an influential technique for solving the fractional PDEs and fractional order problems occurring in the field of engineering, physics etc. Numerical results are obtained for verification and demonstration purpose by using Mathematica software.
State reduced order models for the modelling of the thermal behavior of buildings
Menezo, Christophe; Bouia, Hassan; Roux, Jean-Jacques; Depecker, Patrick [Institute National de Sciences Appliquees de Lyon, Villeurbanne Cedex, (France). Centre de Thermique de Lyon (CETHIL). Equipe Thermique du Batiment]. E-mail: menezo@insa-cethil-etb.insa-lyon.fr; bouia@insa-cethil-etb.insa-lyon.fr; roux@insa-cethil-etb.insa-lyon.fr; depecker@insa-cethil-etb.insa-lyon.fr
2000-07-01
This work is devoted to the field of building physics and related to the reduction of heat conduction models. The aim is to enlarge the model libraries of heat and mass transfer codes through limiting the considerable dimensions reached by the numerical systems during the modelling process of a multizone building. We show that the balanced realization technique, specifically adapted to the coupling of reduced order models with the other thermal phenomena, turns out to be very efficient. (author)
Efficient approximation of sparse Jacobians for time-implicit reduced order models
2014-01-01
This paper introduces a sparse matrix discrete interpolation method to effectively compute matrix approximations in the reduced order modeling framework. The sparse algorithm developed herein relies on the discrete empirical interpolation method and uses only samples of the nonzero entries of the matrix series. The proposed approach can approximate very large matrices, unlike the current matrix discrete empirical interpolation method which is limited by its large computational memory requirem...
Reduced Order Model Implementation in the Risk-Informed Safety Margin Characterization Toolkit
Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rinaldi, Ivan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Dan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Bei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pascucci, Valerio [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-09-01
The RISMC project aims to develop new advanced simulation-based tools to perform Probabilistic Risk Analysis (PRA) for the existing fleet of U.S. nuclear power plants (NPPs). These tools numerically model not only the thermo-hydraulic behavior of the reactor primary and secondary systems but also external events temporal evolution and components/system ageing. Thus, this is not only a multi-physics problem but also a multi-scale problem (both spatial, µm-mm-m, and temporal, ms-s-minutes-years). As part of the RISMC PRA approach, a large amount of computationally expensive simulation runs are required. An important aspect is that even though computational power is regularly growing, the overall computational cost of a RISMC analysis may be not viable for certain cases. A solution that is being evaluated is the use of reduce order modeling techniques. During the FY2015, we investigated and applied reduced order modeling techniques to decrease the RICM analysis computational cost by decreasing the number of simulations runs to perform and employ surrogate models instead of the actual simulation codes. This report focuses on the use of reduced order modeling techniques that can be applied to any RISMC analysis to generate, analyze and visualize data. In particular, we focus on surrogate models that approximate the simulation results but in a much faster time (µs instead of hours/days). We apply reduced order and surrogate modeling techniques to several RISMC types of analyses using RAVEN and RELAP-7 and show the advantages that can be gained.
A Reduced-order NLTE Kinetic Model for Radiating Plasmas of Outer Envelopes of Stellar Atmospheres
Munafò, Alessandro; Mansour, Nagi N.; Panesi, Marco
2017-04-01
The present work proposes a self-consistent reduced-order NLTE kinetic model for radiating plasmas found in the outer layers of stellar atmospheres. A detailed collisional-radiative kinetic mechanism is constructed by leveraging the most up-to-date set of ab initio and experimental data available in the literature. This constitutes the starting point for the derivation of a reduced-order model, obtained by lumping the bound energy states into groups. In order to determine the needed thermo-physical group properties, uniform and Maxwell–Boltzmann energy distributions are used to reconstruct the energy population of each group. Finally, the reduced set of governing equations for the material gas and the radiation field is obtained based on the moment method. Applications consider the steady flow across a shock wave in partially ionized hydrogen. The results clearly demonstrate that adopting a Maxwell–Boltzmann grouping allows, on the one hand, for a substantial reduction of the number of unknowns and, on the other, to maintain accuracy for both gas and radiation quantities. Also, it is observed that, when neglecting line radiation, the use of two groups already leads to a very accurate resolution of the photo-ionization precursor, internal relaxation, and radiative cooling regions. The inclusion of line radiation requires adopting just one additional group to account for optically thin losses in the α, β, and γ lines of the Balmer and Paschen series. This trend has been observed for a wide range of shock wave velocities.
DESIGNING REDUCED-ORDER CONTROLLERS OF MIXED SENSITIVITY PROBLEM FOR FLIGHT CONTROL SYSTEMS
无
2000-01-01
Based on linear matrix inequalities (LMI), the design method of reduced-order controllers of mixed sensitivity problem is studied for flight control systems. It is shown that there exists a controller with order not greater than the difference between the generalized plant order and the number of independent control variables, if the mixed sensitivity problem is solvable for strict regular flight control plants. The proof is constructive, and an approach to design such a controller can be obtained in terms of a pair of feasible solution to the well-known 3 LMI. Finally, an example of mixed sensitivity problem for a flight control system is given to demonstrate practice of the approach.
Test-retest reliability and task order effects of emotional cognitive tests in healthy subjects.
Adams, Thomas; Pounder, Zoe; Preston, Sally; Hanson, Andy; Gallagher, Peter; Harmer, Catherine J; McAllister-Williams, R Hamish
2016-11-01
Little is known of the retest reliability of emotional cognitive tasks or the impact of using different tasks employing similar emotional stimuli within a battery. We investigated this in healthy subjects. We found improved overall performance in an emotional attentional blink task (EABT) with repeat testing at one hour and one week compared to baseline, but the impact of an emotional stimulus on performance was unchanged. Similarly, performance on a facial expression recognition task (FERT) was better one week after a baseline test, though the relative effect of specific emotions was unaltered. There was no effect of repeat testing on an emotional word categorising, recall and recognition task. We found no difference in performance in the FERT and EABT irrespective of task order. We concluded that it is possible to use emotional cognitive tasks in longitudinal studies and combine tasks using emotional facial stimuli in a single battery.
Multi-Level Reduced Order Modeling Equipped with Probabilistic Error Bounds
Abdo, Mohammad Gamal Mohammad Mostafa
model parameters, responses, or state variables, are projected onto lower dimensional subspaces, referred to as the "active subspaces", which are selected to capture a user-defined portion of the snapshots variations. Once determined, the ROM model application involves constraining the variables to the active subspaces. In doing so, the contribution from the variables discarded components can be estimated using a fundamental theorem from random matrix theory which has its roots in Dixon's theory, developed in 1983. This theory was initially presented for linear matrix operators. The thesis extends this theorem's results to allow reduction of general smooth nonlinear operators. The result is an approach by which the adequacy of a given active subspace determined using a given set of snapshots, generated either using the full high fidelity model, or other models with lower fidelity, can be assessed, which provides insight to the analyst on the type of snapshots required to reach a reduction that can satisfy user-defined preset tolerance limits on the reduction errors. Reactor physics calculations are employed as a test bed for the proposed developments. The focus will be on reducing the effective dimensionality of the various data streams such as the cross-section data and the neutron flux. The developed methods will be applied to representative assembly level calculations, where the size of the cross-section and flux spaces are typically large, as required by downstream core calculations, in order to capture the broad range of conditions expected during reactor operation. (Abstract shortened by ProQuest.).
Xiao, D.; Yang, P.; Fang, F.; Xiang, J.; Pain, C. C.; Navon, I. M.; Chen, M.
2017-02-01
This work presents the first application of a non-intrusive reduced order method to model solid interacting with compressible fluid flows to simulate crack initiation and propagation. In the high fidelity model, the coupling process is achieved by introducing a source term into the momentum equation, which represents the effects of forces of the solid on the fluid. A combined single and smeared crack model with the Mohr-Coulomb failure criterion is used to simulate crack initiation and propagation. The non-intrusive reduced order method is then applied to compressible fluid and fractured solid coupled modelling where the computational cost involved in the full high fidelity simulation is high. The non-intrusive reduced order model (NIROM) developed here is constructed through proper orthogonal decomposition (POD) and a radial basis function (RBF) multi-dimensional interpolation method. The performance of the NIROM for solid interacting with compressible fluid flows, in the presence of fracture models, is illustrated by two complex test cases: an immersed wall in a fluid and a blasting test case. The numerical simulation results show that the NIROM is capable of capturing the details of compressible fluids and fractured solids while the CPU time is reduced by several orders of magnitude. In addition, the issue of whether or not to subtract the mean from the snapshots before applying POD is discussed in this paper. It is shown that solutions of the NIROM, without mean subtracted before constructing the POD basis, captured more details than the NIROM with mean subtracted from snapshots.
Ravenzwaay, van B.
2013-01-01
'Many of the in vitro toxicological studies have not been sufficiently validated to determine their applicability domain, even less have gained regulatory acceptance. Major advantage of in vitro testing today is the early identification of significant hazards in compound development and reduced and
Ravenzwaay, van B.
2013-01-01
'Many of the in vitro toxicological studies have not been sufficiently validated to determine their applicability domain, even less have gained regulatory acceptance. Major advantage of in vitro testing today is the early identification of significant hazards in compound development and reduced and
Meeks, E.; Chou, C. -P.; Garratt, T.
2013-03-31
Engineering simulations of coal gasifiers are typically performed using computational fluid dynamics (CFD) software, where a 3-D representation of the gasifier equipment is used to model the fluid flow in the gasifier and source terms from the coal gasification process are captured using discrete-phase model source terms. Simulations using this approach can be very time consuming, making it difficult to imbed such models into overall system simulations for plant design and optimization. For such system-level designs, process flowsheet software is typically used, such as Aspen Plus® [1], where each component where each component is modeled using a reduced-order model. For advanced power-generation systems, such as integrated gasifier/gas-turbine combined-cycle systems (IGCC), the critical components determining overall process efficiency and emissions are usually the gasifier and combustor. Providing more accurate and more computationally efficient reduced-order models for these components, then, enables much more effective plant-level design optimization and design for control. Based on the CHEMKIN-PRO and ENERGICO software, we have developed an automated methodology for generating an advanced form of reduced-order model for gasifiers and combustors. The reducedorder model offers representation of key unit operations in flowsheet simulations, while allowing simulation that is fast enough to be used in iterative flowsheet calculations. Using high-fidelity fluiddynamics models as input, Reaction Design’s ENERGICO® [2] software can automatically extract equivalent reactor networks (ERNs) from a CFD solution. For the advanced reduced-order concept, we introduce into the ERN a much more detailed kinetics model than can be included practically in the CFD simulation. The state-of-the-art chemistry solver technology within CHEMKIN-PRO allows that to be accomplished while still maintaining a very fast model turn-around time. In this way, the ERN becomes the basis for
Commentary – ordering lab tests for suspected rheumatic disease
Jarvis James N
2008-11-01
Full Text Available Abstract One of the least-appreciated advances in pediatric rheumatology over the past 25 years has been the delineation of the many ways in which children with rheumatic disease differ from adults with the same illnesses. Furthermore, we are now learning that paradigms that are useful in evaluating adults with musculoskeletal complaints have limited utility in children. Nowhere is that more true than in the use of commonly used laboratory tests, particularly antinuclear antibody (ANA and rheumatoid factor (RF assays. This short review will provide the practitioner with the evidence base that supports a more limited use of ANA and RF testing in children.
How to reduce errors in applying impairment tests
Petersen, Christian; Plenborg, Thomas
2007-01-01
Fair value accounting has become predominant in accounting as a vast number of IAS/IFRS standards are based on fair value accounting, including IAS 36 Impairment of assets. Fair value accounting for goodwill is technically challenging, since market prices are not observable. Thus, valuation technologies must be applied in order to test goodwill for impairment. While prior research on goodwill has concentrated on either the (dis)advantages for each accounting procedure for goodwill or exami...
Testing First-Order Logic Axioms in AutoCert
Ahn, Ki Yung; Denney, Ewen
2009-01-01
AutoCert [2] is a formal verification tool for machine generated code in safety critical domains, such as aerospace control code generated from MathWorks Real-Time Workshop. AutoCert uses Automated Theorem Provers (ATPs) [5] based on First-Order Logic (FOL) to formally verify safety and functional correctness properties of the code. These ATPs try to build proofs based on user provided domain-specific axioms, which can be arbitrary First-Order Formulas (FOFs). These axioms are the most crucial part of the trusted base, since proofs can be submitted to a proof checker removing the need to trust the prover and AutoCert itself plays the part of checking the code generator. However, formulating axioms correctly (i.e. precisely as the user had really intended) is non-trivial in practice. The challenge of axiomatization arise from several dimensions. First, the domain knowledge has its own complexity. AutoCert has been used to verify mathematical requirements on navigation software that carries out various geometric coordinate transformations involving matrices and quaternions. Axiomatic theories for such constructs are complex enough that mistakes are not uncommon. Second, adjusting axioms for ATPs can add even more complexity. The axioms frequently need to be modified in order to have them in a form suitable for use with ATPs. Such modifications tend to obscure the axioms further. Thirdly, speculating validity of the axioms from the output of existing ATPs is very hard since theorem provers typically do not give any examples or counterexamples.
Sampling Strategies for Reduced-Order Modeling of Nonlinear and Unsteady Aerodynamics
2014-01-13
topologies using a cell-centered finite volume method. Second-order accuracy in space is achieved using the exact Riemann solver of Gottlieb and Groth,18...attack zero during the rotation, the grid moves right and upward. III. Test Case The X-31 aircraft is considered in this paper. The aircraft geometry ...Department of Defense Engineering Research Development Center (ERDC). The X-31 geometry was provided by NATO RTO Task Group AVT-161 on Assessment of
Bogaers, Alfred EJ
2010-01-01
Full Text Available = 30 units, with the initial mesh shown in Figure 1(a). The contour plots use an element shape-size quality indicator defined in [9], where 0 ? fss ? 1, for degenerate and perfect elements respectively. 4.1 Snapshot Generation The first requirement... mesh, generated using NETGEN [17]. (b) Full order mesh optimization. (c) ROM: Coefficient Interpolation. (d) ROM: Coefficient Optimization. Figure 1: Rotation and translation test case. Mesh quality contour plots using quality metric 0 ? fss ? 1 [3...
Instrumented impact testing machine with reduced specimen oscillation effects
Rintamaa, R.; Ranka, K.; Wallin, K.; Ikonen, K.; Talja, H.; Kotilainen, H.; Sirkkola, E.
1984-07-01
A pendulum-type instrumented Charpy test apparatus based on inverted test geometry was developed. Geometry inversion reduces inertia load and specimen oscillation effects. Initial impact energy is double that of standard (300 J) impact testers, allowing the use of larger (10 x 20 x 110 mm) bend specimens than normal Charpy specimens. The rotation axis in the three point bending is nearly stationary, making COD-measurements possible. Inertia effects and specimen oscillations are compared with the conventional tester, and using an analytical finite element model for Charpy V-notch specimens. Better performance for the inverted geometry is reported.
Babaee, Hessam; Farazmand, Mohamad; Haller, George; Sapsis, Themistoklis P.
2017-06-01
High-dimensional chaotic dynamical systems can exhibit strongly transient features. These are often associated with instabilities that have a finite-time duration. Because of the finite-time character of these transient events, their detection through infinite-time methods, e.g., long term averages, Lyapunov exponents or information about the statistical steady-state, is not possible. Here, we utilize a recently developed framework, the Optimally Time-Dependent (OTD) modes, to extract a time-dependent subspace that spans the modes associated with transient features associated with finite-time instabilities. As the main result, we prove that the OTD modes, under appropriate conditions, converge exponentially fast to the eigendirections of the Cauchy-Green tensor associated with the most intense finite-time instabilities. Based on this observation, we develop a reduced-order method for the computation of finite-time Lyapunov exponents (FTLE) and vectors. In high-dimensional systems, the computational cost of the reduced-order method is orders of magnitude lower than the full FTLE computation. We demonstrate the validity of the theoretical findings on two numerical examples.
Babaee, Hessam; Farazmand, Mohamad; Haller, George; Sapsis, Themistoklis P
2017-06-01
High-dimensional chaotic dynamical systems can exhibit strongly transient features. These are often associated with instabilities that have a finite-time duration. Because of the finite-time character of these transient events, their detection through infinite-time methods, e.g., long term averages, Lyapunov exponents or information about the statistical steady-state, is not possible. Here, we utilize a recently developed framework, the Optimally Time-Dependent (OTD) modes, to extract a time-dependent subspace that spans the modes associated with transient features associated with finite-time instabilities. As the main result, we prove that the OTD modes, under appropriate conditions, converge exponentially fast to the eigendirections of the Cauchy-Green tensor associated with the most intense finite-time instabilities. Based on this observation, we develop a reduced-order method for the computation of finite-time Lyapunov exponents (FTLE) and vectors. In high-dimensional systems, the computational cost of the reduced-order method is orders of magnitude lower than the full FTLE computation. We demonstrate the validity of the theoretical findings on two numerical examples.
Reduced Order Modeling of Bubble Cloud Dynamics in a Focused Ultrasound Field
Maeda, Kazuki; Colonius, Tim
2016-11-01
In order to characterize the cloud cavitation in burst wave lithotripsy, reduced order modeling of the dynamics of a spherical bubble cloud of a radius O (1) mm interacting with traveling ultrasound waves of an amplitude O(1) MPa in water is presented. Bubbles are treated as spherical, radially oscillating cavities dispersed in continuous liquid phase. The volume of Lagrangian point bubbles is mapped with a regularization kernel as void fraction onto three-dimensional Cartesian grids that define the Eulerian liquid phase. The flow field is solved using a WENO-based compressible flow solver. The initial size and number density of the bubbles are critical for their coherent dynamics in the cloud, yet three-dimensional simulations of clouds with various parameters are computationally demanding. For further reduced-order modeling, a new kernel is introduce into the model to regularize bubbles onto two-dimensional, axisymmetric grids. The evolution of the void fraction and the maximum pressure in the cloud simulated using the model agree with results of three-dimensional simulations, while the reduction in computational cost is a factor of O (100) . Finally, the model is applied to a parametric study of the coherent dynamics of bubbles.
Reduced-Order Modeling for Flutter/LCO Using Recurrent Artificial Neural Network
Yao, Weigang; Liou, Meng-Sing
2012-01-01
The present study demonstrates the efficacy of a recurrent artificial neural network to provide a high fidelity time-dependent nonlinear reduced-order model (ROM) for flutter/limit-cycle oscillation (LCO) modeling. An artificial neural network is a relatively straightforward nonlinear method for modeling an input-output relationship from a set of known data, for which we use the radial basis function (RBF) with its parameters determined through a training process. The resulting RBF neural network, however, is only static and is not yet adequate for an application to problems of dynamic nature. The recurrent neural network method [1] is applied to construct a reduced order model resulting from a series of high-fidelity time-dependent data of aero-elastic simulations. Once the RBF neural network ROM is constructed properly, an accurate approximate solution can be obtained at a fraction of the cost of a full-order computation. The method derived during the study has been validated for predicting nonlinear aerodynamic forces in transonic flow and is capable of accurate flutter/LCO simulations. The obtained results indicate that the present recurrent RBF neural network is accurate and efficient for nonlinear aero-elastic system analysis
Reduced-Order Modeling for Flutter/LCO Using Recurrent Artificial Neural Network
Yao, Weigang; Liou, Meng-Sing
2012-01-01
The present study demonstrates the efficacy of a recurrent artificial neural network to provide a high fidelity time-dependent nonlinear reduced-order model (ROM) for flutter/limit-cycle oscillation (LCO) modeling. An artificial neural network is a relatively straightforward nonlinear method for modeling an input-output relationship from a set of known data, for which we use the radial basis function (RBF) with its parameters determined through a training process. The resulting RBF neural network, however, is only static and is not yet adequate for an application to problems of dynamic nature. The recurrent neural network method [1] is applied to construct a reduced order model resulting from a series of high-fidelity time-dependent data of aero-elastic simulations. Once the RBF neural network ROM is constructed properly, an accurate approximate solution can be obtained at a fraction of the cost of a full-order computation. The method derived during the study has been validated for predicting nonlinear aerodynamic forces in transonic flow and is capable of accurate flutter/LCO simulations. The obtained results indicate that the present recurrent RBF neural network is accurate and efficient for nonlinear aero-elastic system analysis
REVEAL: An Extensible Reduced Order Model Builder for Simulation and Modeling
Agarwal, Khushbu; Sharma, Poorva; Ma, Jinliang; Lo, Chaomei; Gorton, Ian; Liu, Yan
2013-04-30
Many science domains need to build computationally efficient and accurate representations of high fidelity, computationally expensive simulations. These computationally efficient versions are known as reduced-order models. This paper presents the design and implementation of a novel reduced-order model (ROM) builder, the REVEAL toolset. This toolset generates ROMs based on science- and engineering-domain specific simulations executed on high performance computing (HPC) platforms. The toolset encompasses a range of sampling and regression methods that can be used to generate a ROM, automatically quantifies the ROM accuracy, and provides support for an iterative approach to improve ROM accuracy. REVEAL is designed to be extensible in order to utilize the core functionality with any simulator that has published input and output formats. It also defines programmatic interfaces to include new sampling and regression techniques so that users can ‘mix and match’ mathematical techniques to best suit the characteristics of their model. In this paper, we describe the architecture of REVEAL and demonstrate its usage with a computational fluid dynamics model used in carbon capture.
Muruganandi, G.; Saravanan, M.; Vinitha, G.; Jessie Raj, M. B.; Sabari Girisun, T. C.
2017-05-01
Reduced graphene oxide (rGO) was prepared by reduction method using various reductants like hydrazine, sodium borohydride and ascorbic acid. XRD and Raman analysis confirmed the effective removal of functional groups in GO. SEM revealed that rGO consists of thin crumpled and disordered sheets closely associated with each other. Blue shift in UV-absorption maxima was due to weak interlayer coupling between the layers of rGO. Third order NLO properties of dispersed rGO were measured by Z-scan technique (532 nm, 50 mW). Both GO and rGO possess self defocusing, saturable absorption and optical limiting behavior. The nonlinear component of refractive index, absorption coefficient and optical susceptibility were found to be 10-8 cm2/W, 10-3 cm/W and 10-6 esu respectively. Tunability of NLO coefficients with altering functional groups upon rGO was achieved. rGO prepared using hydrazine with high NLO coefficient and excellent durability, signify the scope of utilizing them as optical limiters.
De Melo, Hermes Teixeria; Dwyer, Francis M.
This study investigated the effects of (1) verbal instruction alone vs. verbal instruction complemented by simple line drawings; (2) visual testing vs. nonvisual testing; (3) verbal cueing vs. free recall on achievement; and (4) order of testing on subsequent achievement. Interactions among type of instruction, type of testing, and order of…
Zuo-Hua Li
2017-01-01
Full Text Available Time-delays of control force calculation, data acquisition, and actuator response will degrade the performance of Active Mass Damper (AMD control systems. To reduce the influence, model reduction method is used to deal with the original controlled structure. However, during the procedure, the related hierarchy information of small eigenvalues will be directly discorded. As a result, the reduced-order model ignores the information of high-order mode, which will reduce the design accuracy of an AMD control system. In this paper, a new reduced-order controller based on the improved Balanced Truncation (BT method is designed to reduce the calculation time and to retain the abandoned high-order modal information. It includes high-order natural frequency, damping ratio, and vibration modal information of the original structure. Then, a control gain design method based on Guaranteed Cost Control (GCC algorithm is presented to eliminate the adverse effects of data acquisition and actuator response time-delays in the design process of the reduced-order controller. To verify its effectiveness, the proposed methodology is applied to a numerical example of a ten-storey frame and an experiment of a single-span four-storey steel frame. Both numerical and experimental results demonstrate that the reduced-order controller with GCC algorithm has an excellent control effect; meanwhile it can compensate time-delays effectively.
Xuliang Yao
2017-01-01
Full Text Available The attitude control and depth tracking issue of autonomous underwater vehicle (AUV are addressed in this paper. By introducing a nonsingular coordinate transformation, a novel nonlinear reduced-order observer (NROO is presented to achieve an accurate estimation of AUV’s state variables. A discrete-time model predictive control with nonlinear model online linearization (MPC-NMOL is applied to enhance the attitude control and depth tracking performance of AUV considering the wave disturbance near surface. In AUV longitudinal control simulation, the comparisons have been presented between NROO and full-order observer (FOO and also between MPC-NMOL and traditional NMPC. Simulation results show the effectiveness of the proposed method.
Enhanced ordering reduces electric susceptibility of liquids confined to graphene slit pores
Terrones, Jeronimo; Kiley, Patrick J.; Elliott, James A.
2016-06-01
The behaviours of a range of polar and non-polar organic liquids (acetone, ethanol, methanol, N-methyl-2-pyrrolidone (NMP), carbon tetrachloride and water) confined to 2D graphene nanochannels with thicknesses in the range of 4.5 Å to 40 Å were studied using classical molecular dynamics and hybrid density functional theory. All liquids were found to organise spontaneously into ordered layers parallel to the confining surfaces, with those containing polar molecules having their electric dipoles aligned parallel to such surfaces. In particular, monolayers of NMP showed remarkable in-plane ordering and low molecular mobility, suggesting the existence of a previously unknown 2D solid-like phase. Calculations for polar liquids showed dramatically reduced static permittivities normal to the confining surfaces; these changes are expected to improve electron tunnelling across the liquid films, modifying the DC electrical properties of immersed assemblies of carbon nanomaterials.
Enhanced ordering reduces electric susceptibility of liquids confined to graphene slit pores
Terrones, Jeronimo; Kiley, Patrick J.; Elliott, James A.
2016-01-01
The behaviours of a range of polar and non-polar organic liquids (acetone, ethanol, methanol, N-methyl-2-pyrrolidone (NMP), carbon tetrachloride and water) confined to 2D graphene nanochannels with thicknesses in the range of 4.5 Å to 40 Å were studied using classical molecular dynamics and hybrid density functional theory. All liquids were found to organise spontaneously into ordered layers parallel to the confining surfaces, with those containing polar molecules having their electric dipoles aligned parallel to such surfaces. In particular, monolayers of NMP showed remarkable in-plane ordering and low molecular mobility, suggesting the existence of a previously unknown 2D solid-like phase. Calculations for polar liquids showed dramatically reduced static permittivities normal to the confining surfaces; these changes are expected to improve electron tunnelling across the liquid films, modifying the DC electrical properties of immersed assemblies of carbon nanomaterials. PMID:27265098
Silveira, L.M.; Kamon, M.; Elfadel, I.; White, J. [Massachusetts Inst. of Technology, Cambridge, MA (United States)
1996-12-31
Model order reduction based on Krylov subspace iterative methods has recently emerged as a major tool for compressing the number of states in linear models used for simulating very large physical systems (VLSI circuits, electromagnetic interactions). There are currently two main methods for accomplishing such a compression: one is based on the nonsymmetric look-ahead Lanczos algorithm that gives a numerically stable procedure for finding Pade approximations, while the other is based on a less well characterized Arnoldi algorithm. In this paper, we show that for certain classes of generalized state-space systems, the reduced-order models produced by a coordinate-transformed Arnoldi algorithm inherit the stability of the original system. Complete Proofs of our results will be given in the final paper.
Damping by parametric excitation in a set of reduced-order cracked rotor systems
Kulesza, Zbigniew; Sawicki, Jerzy T.
2015-10-01
A common tool utilized for the stability analysis of parametrically excited linear systems, such as rotors with cracked shafts, is Floquet's method. The disadvantage is a long calculation time needed to evaluate the monodromy matrix and instability zones. An efficient alternative is the generalized Bolotin's method, where the instability zones are evaluated quickly, yet the matrices that must be calculated are of large dimensions. In the present paper, the stability analysis is conducted with both Floquet's method and the generalized Bolotin's method. However, the order of the model is reduced to two modes only and stability analyses are performed for the second-order systems obtained with various combinations of the reducing modes. Then, the results of such analyses are collected in an overall stability map. The stability map obtained in this way closely reconstructs the stability map calculated with the full-order model of the rotor, yet the calculation time needed to generate the collected map as well as the dimension of the problem are considerably reduced. The approach is demonstrated with a mathematical model of the machine with the breathing crack modeled using the rigid finite element method. The rotor is not rotating, yet the stiffness of the shaft is varied periodically to simulate the parametric excitation. An interesting indication of the developing shaft crack observed in the generated stability maps is the presence of anti-resonant zones, where the rotor vibration amplitudes quickly decay. It is anticipated that this phenomenon of increased damping at specific excitation frequencies may have potential application for shaft crack detection.
Ruzziconi, Laura
2013-06-10
We present a study of the dynamic behavior of a microelectromechanical systems (MEMS) device consisting of an imperfect clamped-clamped microbeam subjected to electrostatic and electrodynamic actuation. Our objective is to develop a theoretical analysis, which is able to describe and predict all the main relevant aspects of the experimental response. Extensive experimental investigation is conducted, where the main imperfections coming from microfabrication are detected, the first four experimental natural frequencies are identified and the nonlinear dynamics are explored at increasing values of electrodynamic excitation, in a neighborhood of the first symmetric resonance. Several backward and forward frequency sweeps are acquired. The nonlinear behavior is highlighted, which includes ranges of multistability, where the nonresonant and the resonant branch coexist, and intervals where superharmonic resonances are clearly visible. Numerical simulations are performed. Initially, two single mode reduced-order models are considered. One is generated via the Galerkin technique, and the other one via the combined use of the Ritz method and the Padé approximation. Both of them are able to provide a satisfactory agreement with the experimental data. This occurs not only at low values of electrodynamic excitation, but also at higher ones. Their computational efficiency is discussed in detail, since this is an essential aspect for systematic local and global simulations. Finally, the theoretical analysis is further improved and a two-degree-of-freedom reduced-order model is developed, which is also capable of capturing the measured second symmetric superharmonic resonance. Despite the apparent simplicity, it is shown that all the proposed reduced-order models are able to describe the experimental complex nonlinear dynamics of the device accurately and properly, which validates the proposed theoretical approach. © 2013 IOP Publishing Ltd.
Distributed non-cooperative robust MPC based on reduced-order models
Yushen LONG; Shuai LIU; Lihua XIE; Karl Henrik JOHANSSON
2016-01-01
In this paper, a non-cooperative distributed MPC algorithm based on reduced order model is proposed to stabilize large-scale systems. The large-scale system consists of a group of interconnected subsystems. Each subsystem can be partitioned into two parts:measurable part, whose states can be directly measured by sensors, and the unmeasurable part. In the online computation phase, only the measurable dynamics of the corresponding subsystem and neighbour-to-neighbour communication are necessary for the local controller design. Satisfaction of the state constraints and the practical stability are guaranteed while the complexity of the optimization problem is reduced. Numerical examples are given to show the effectiveness of this algorithm.
YU FENG; WEIQUAN PAN
2017-04-01
By introducing an additional state feedback into classic Rikitake system, a new hyperchaotic system without equilibrium is derived. The proposed system is investigated through numerical simulations and analyses including time phase portraits, Lyapunov exponents, and Poincaré maps. Based on adaptive control and Lyapunov stability theory, we design a reduced-order projective synchronization scheme for synchronizing the hyperchaotic Rikitake system coexisting without equilibria and the original classic Rikitake system coexisting with two non-hyperbolic equilibria. Finally, numerical simulations are given to illustrate the effectiveness of the proposedsynchronization scheme.
Heller, Johann; Van Rienen, Ursula; 10.1016/j.phpro.2015.11.060
2015-01-01
The computation of electromagnetic fields and parameters derived thereof for lossless radio frequency (RF) structures filled with isotropic media is an important task for the design and operation of particle accelerators. Unfortunately, these computations are often highly demanding with regard to computational effort. The entire computational demand of the problem can be reduced using decomposition schemes in order to solve the field problems on standard workstations. This paper presents one of the first detailed comparisons between the recently proposed state-space concatenation approach (SSC) and a direct computation for an accelerator cavity with coupler-elements that break the rotational symmetry.
POD/MAC-Based Modal Basis Selection for a Reduced Order Nonlinear Response Analysis
Rizzi, Stephen A.; Przekop, Adam
2007-01-01
A feasibility study was conducted to explore the applicability of a POD/MAC basis selection technique to a nonlinear structural response analysis. For the case studied the application of the POD/MAC technique resulted in a substantial improvement of the reduced order simulation when compared to a classic approach utilizing only low frequency modes present in the excitation bandwidth. Further studies are aimed to expand application of the presented technique to more complex structures including non-planar and two-dimensional configurations. For non-planar structures the separation of different displacement components may not be necessary or desirable.
Arbitrary Lagrangian-Eulerian approach in reduced order modeling of a flow with a moving boundary
Stankiewicz, W.; Roszak, R.; Morzyński, M.
2013-06-01
Flow-induced deflections of aircraft structures result in oscillations that might turn into such a dangerous phenomena like flutter or buffeting. In this paper the design of an aeroelastic system consisting of Reduced Order Model (ROM) of the flow with a moving boundary is presented. The model is based on Galerkin projection of governing equation onto space spanned by modes obtained from high-fidelity computations. The motion of the boundary and mesh is defined in Arbitrary Lagrangian-Eulerian (ALE) approach and results in additional convective term in Galerkin system. The developed system is demonstrated on the example of a flow around an oscillating wing.
Chaos control and reduced-order generalized synchronization for the Chen-Liao system
Li Rui-Hong; Xu Wei; Li Shuang
2007-01-01
This paper deals with the problem of chaos control and synchronization of the Chen-Liao system. Prom rigorous mathematic justification, the chaotic trajectories of the Chen-Liao system are led to a type of points whose four-dimensional coordinates have a particular functional relation among them. Meanwhile, a new synchronization manner, reduced-order generalized synchronization (RGS), is proposed which has the characteristic of having a functional relation between the slave and the partial master systems. It is shown that this new synchronization phenomenon can be realized by a novel technique. Numerical simulations have verified the effectiveness of the proposed scheme.
Deformation behavior of reduced activation ferritic steel during tensile test
Shiba, Kiyoyuki [Department of Material Science and Engineering, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibakaki 319-1195 (Japan)]. E-mail: shiba@realab01.tokai.jaeri.go.jp; Hirose, Takanori [Department of Fusion Engineering Research, Japan Atomic Energy Research Institute, 801-1 Mukouyama, Naka, Ibaraki 311-0193 (Japan)
2006-02-15
Deformation behavior of reduced activation martensitic steel F82H during tensile tests were studied. True stress-true strain diagrams were calculated with minimum diameter determined from the specimen profile obtained by laser micro-gauge scanning the diameter along the longitudinal direction during tensile test. Cylindrical specimens of F82H were used for the measurement and test temperatures were room temperature (RT), 300, 400, 500 and 600 deg. C. Tensile tests were carried out with 1 x 10{sup -4} s{sup -1} of strain rate. Other strain rates (1 x 10{sup -3} and 1 x 10{sup -5} s{sup -1}) were applied for the tests at RT. Although uniform elongation of F82H is relatively small at elevated temperature, true stress increases to fracture after necking starts. True stress decreases temporarily after yielding at 600 deg. C, but it increases again to fracture like the specimens tested at lower temperatures. Influence of strain rate to true stress-true strain relationship at room temperature was small, but unstable deformation occurred in narrower area at higher strain rate.
YAN ShiYu; SUN ZengQi
2009-01-01
This paper designs and analyzes switching fuzzy reduced-order observer and proves that the corresponding separation principle does hold. A numerical simulation and comparison with smooth fuzzy full-order observer are given to assess switching fuzzy reduced-order observer and the validity of the separation principles.
Reduced Order Modeling for Prediction and Control of Large-Scale Systems.
Kalashnikova, Irina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Computational Mathematics; Arunajatesan, Srinivasan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Aerosciences Dept.; Barone, Matthew Franklin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Aerosciences Dept.; van Bloemen Waanders, Bart Gustaaf [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Uncertainty Quantification and Optimization Dept.; Fike, Jeffrey A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Component Science and Mechanics Dept.
2014-05-01
This report describes work performed from June 2012 through May 2014 as a part of a Sandia Early Career Laboratory Directed Research and Development (LDRD) project led by the first author. The objective of the project is to investigate methods for building stable and efficient proper orthogonal decomposition (POD)/Galerkin reduced order models (ROMs): models derived from a sequence of high-fidelity simulations but having a much lower computational cost. Since they are, by construction, small and fast, ROMs can enable real-time simulations of complex systems for onthe- spot analysis, control and decision-making in the presence of uncertainty. Of particular interest to Sandia is the use of ROMs for the quantification of the compressible captive-carry environment, simulated for the design and qualification of nuclear weapons systems. It is an unfortunate reality that many ROM techniques are computationally intractable or lack an a priori stability guarantee for compressible flows. For this reason, this LDRD project focuses on the development of techniques for building provably stable projection-based ROMs. Model reduction approaches based on continuous as well as discrete projection are considered. In the first part of this report, an approach for building energy-stable Galerkin ROMs for linear hyperbolic or incompletely parabolic systems of partial differential equations (PDEs) using continuous projection is developed. The key idea is to apply a transformation induced by the Lyapunov function for the system, and to build the ROM in the transformed variables. It is shown that, for many PDE systems including the linearized compressible Euler and linearized compressible Navier-Stokes equations, the desired transformation is induced by a special inner product, termed the “symmetry inner product”. Attention is then turned to nonlinear conservation laws. A new transformation and corresponding energy-based inner product for the full nonlinear compressible Navier
A reduced-order representation of the Schrödinger equation
Ming-C. Cheng
2016-09-01
Full Text Available A reduced-order-based representation of the Schrödinger equation is investigated for electron wave functions in semiconductor nanostructures. In this representation, the Schrödinger equation is projected onto an eigenspace described by a small number of basis functions that are generated from the proper orthogonal decomposition (POD. The approach substantially reduces the numerical degrees of freedom (DOF’s needed to numerically solve the Schrödinger equation for the wave functions and eigenstate energies in a quantum structure and offers an accurate solution as detailed as the direct numerical simulation of the Schrödinger equation. To develop such an approach, numerical data accounting for parametric variations of the system are used to perform decomposition in order to generate the POD eigenvalues and eigenvectors for the system. This approach is applied to develop POD models for single and multiple quantum well structure. Errors resulting from the approach are examined in detail associated with the selected numerical DOF’s of the POD model and quality of data used for generation of the POD eigenvalues and basis functions. This study investigates the fundamental concepts of the POD approach to the Schrödinger equation and paves a way toward developing an efficient modeling methodology for large-scale multi-block simulation of quantum nanostructures.
A reduced-order representation of the Schrödinger equation
Cheng, Ming-C.
2016-09-01
A reduced-order-based representation of the Schrödinger equation is investigated for electron wave functions in semiconductor nanostructures. In this representation, the Schrödinger equation is projected onto an eigenspace described by a small number of basis functions that are generated from the proper orthogonal decomposition (POD). The approach substantially reduces the numerical degrees of freedom (DOF's) needed to numerically solve the Schrödinger equation for the wave functions and eigenstate energies in a quantum structure and offers an accurate solution as detailed as the direct numerical simulation of the Schrödinger equation. To develop such an approach, numerical data accounting for parametric variations of the system are used to perform decomposition in order to generate the POD eigenvalues and eigenvectors for the system. This approach is applied to develop POD models for single and multiple quantum well structure. Errors resulting from the approach are examined in detail associated with the selected numerical DOF's of the POD model and quality of data used for generation of the POD eigenvalues and basis functions. This study investigates the fundamental concepts of the POD approach to the Schrödinger equation and paves a way toward developing an efficient modeling methodology for large-scale multi-block simulation of quantum nanostructures.
Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture
Agaie, Baba G.; Khan, Ilyas; Alshomrani, Ali Saleh; Alqahtani, Aisha M.
2017-05-01
In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.
Reduced order model for binary neutron star waveforms with tidal interactions
Lackey, Benjamin; Bernuzzi, Sebastiano; Galley, Chad
2016-03-01
Observations of inspiralling binary neutron star (BNS) systems with Advanced LIGO can be used to determine the unknown neutron-star equation of state by measuring the phase shift in the gravitational waveform due to tidal interactions. Unfortunately, this requires computationally efficient waveform models for use in parameter estimation codes that typically require 106-107 sequential waveform evaluations, as well as accurate waveform models with phase errors less than 1 radian over the entire inspiral to avoid systematic errors in the measured tidal deformability. The effective one body waveform model with l = 2 , 3, and 4 tidal multipole moments is currently the most accurate model for BNS systems, but takes several minutes to evaluate. We develop a reduced order model of this waveform by constructing separate orthonormal bases for the amplitude and phase evolution. We find that only 10-20 bases are needed to reconstruct any BNS waveform with a starting frequency of 10 Hz. The coefficients of these bases are found with Chebyshev interpolation over the waveform parameter space. This reduced order model has maximum errors of 0.2 radians, and results in a speedup factor of more than 103, allowing parameter estimation codes to run in days to weeks rather than decades.
Wagner, M.
2010-10-01
The inherent variability of the solar resource presents a unique challenge for CSP systems. Incident solar irradiation can fluctuate widely over a short time scale, but plant performance must be assessed for long time periods. As a result, annual simulations with hourly (or sub-hourly) timesteps are the norm in CSP analysis. A highly detailed power cycle model provides accuracy but tends to suffer from prohibitively long run-times; alternatively, simplified empirical models can run quickly but don?t always provide enough information, accuracy, or flexibility for the modeler. The ideal model for feasibility-level analysis incorporates both the detail and accuracy of a first-principle model with the low computational load of a regression model. The work presented in this paper proposes a methodology for organizing and extracting information from the performance output of a detailed model, then using it to develop a flexible reduced-order regression model in a systematic and structured way. A similar but less generalized approach for characterizing power cycle performance and a reduced-order modeling methodology for CFD analysis of heat transfer from electronic devices have been presented. This paper builds on these publications and the non-dimensional approach originally described.
Reduced-Order Models for Load Management in the Power Grid
Alizadeh, Mahnoosh
In recent years, considerable research efforts have been directed towards designing control schemes that can leverage the inherent flexibility of electricity demand that is not tapped into in today's electricity markets. It is expected that these control schemes will be carried out by for-profit entities referred to as aggregators that operate at the edge of the power grid network. While the aggregator control problem is receiving much attention, more high-level questions of how these aggregators should plan their market participation, interact with the main grid and with each other, remain rather understudied. Answering these questions requires a large-scale model for the aggregate flexibility that can be harnessed from the a population of customers, particularly for residences and small businesses. The contribution of this thesis towards this goal is divided into three parts: In Chapter 3, a reduced-order model for a large population of heterogeneous appliances is provided by clustering load profiles that share similar degrees of freedom together. The use of such reduced-order model for system planning and optimal market decision making requires a foresighted approximation of the number of appliances that will join each cluster. Thus, Chapter 4 provides a systematic framework to generate such forecasts for the case of Electric Vehicles, based on real-world battery charging data. While these two chapters set aside the economic side that is naturally involved with participation in demand response programs and mainly focus on the control problem, Chapter 5 is dedicated to the study of optimal pricing mechanisms in order to recruit heterogeneous customers in a demand response program in which an aggregator can directly manage their appliances' load under their specified preferences. Prices are proportional to the wholesale market savings that can result from each recruitment event.
Reduced enrichment for research and test reactors: Proceedings
1993-08-01
November 9--10, 1978, marked the first of what has become an annual event--the International Meeting on Reduced Enrichment for Research and Test Reactors (RERTR). The meeting brought together for the first time many people who became major program participants in later years. This first meeting emphasized fuel development, and it established the basis for all later meetings. Believing that the proceedings of this first meeting are important as a historical record of the beginning of the international RERTR effort. This report provides presentations and discussions of this original meeting. Individual papers have been cataloged separately.
Application of reduced-order controller to turbulent flows for drag reduction
Lee, Keun H.; Cortelezzi, Luca; Kim, John; Speyer, Jason
2001-05-01
A reduced-order linear feedback controller is designed and applied to turbulent channel flow for drag reduction. From the linearized two-dimensional Navier-Stokes equations a distributed feedback controller, which produces blowing/suction at the wall based on the measured turbulent streamwise wall-shear stress, is derived using model reduction techniques and linearquadratic-Gaussian/loop-transfer-recovery control synthesis. The quadratic cost criterion used for synthesis is composed of the streamwise wall-shear stress, which includes the control effort of blowing/suction. This distributed two-dimensional controller developed from a linear system theory is shown to reduce the skin friction by 10% in direct numerical simulations of a low-Reynolds number turbulent nonlinear channel flow. Spanwise shear-stress variation, not captured by the distributed two-dimensional controller, is suppressed by augmentation of a simple spanwise ad hoc control scheme. This augmented three-dimensional controller, which requires only the turbulent streamwise velocity gradient, results in a further reduction in the skin-friction drag. It is shown that the input power requirement is significantly less than the power saved by reduced drag. Other turbulence characteristics affected by these controllers are also discussed.
National Aeronautics and Space Administration — The overall goal of the project is to develop reliable reduced order modeling technologies to automatically generate nonlinear, parameter-varying (PV),...
Origin of how steam rockets can reduce space transport cost by orders of magnitude
Zuppero, Anthony; Larson, Thomas K.; Schnitzler, Bruce G.; Werner, James E.; Rice, John W.; Hill, Thomas J.; Richins, William D.; Parlier, Lynn
1999-01-01
A brief sketch shows the origin of why and how thermal rocket propulsion has the unique potential to dramatically reduce the cost of space transportation for most inner solar system missions of interest. Orders of magnitude reduction in cost are apparently possible when compared to all processes requiring electrolysis for the production of rocket fuels or propellants and to all electric propulsion systems. An order of magnitude advantage can be attributed to rocket propellant tank factors associated with storing water propellant, compared to cryogenic liquids. An order of magnitude can also be attributed to the simplicity of the extraction and processing of ice on the lunar surface, into an easily stored, non-cryogenic rocket propellant (water). A nuclear heated thermal rocket can deliver thousands of times its mass to Low Earth Orbit from the Lunar surface, providing the equivalent to orders of magnitude drop in launch cost for mass in Earth orbit. Mass includes water ice. These cost reductions depend (exponentially) on the mission delta-v requirements being less than about 6 km/s, or about 3 times the specific velocity of steam rockets (2 km/s, from Isp 200 sec). Such missions include: from the lunar surface to Low Lunar Orbit, (LLO), from LLO to lunar escape, from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO), from LEO to Earth Escape, from LEO to Mars Transfer Orbit, from LLO to GEO, missions returning payloads from about 10% of the periodic comets using propulsive capture to orbits around Earth itself, and fast, 100 day missions from Lunar Escape to Mars. All the assertions depend entirely and completely on the existence of abundant, nearly pure ice at the permanently dark North and South Poles of the Moon.
Physically-Based Reduced Order Modelling of a Uni-Axial Polysilicon MEMS Accelerometer
Sarah Zerbini
2012-10-01
Full Text Available In this paper, the mechanical response of a commercial off-the-shelf, uni-axial polysilicon MEMS accelerometer subject to drops is numerically investigated. To speed up the calculations, a simplified physically-based (beams and plate, two degrees of freedom model of the movable parts of the sensor is adopted. The capability and the accuracy of the model are assessed against three-dimensional finite element simulations, and against outcomes of experiments on instrumented samples. It is shown that the reduced order model provides accurate outcomes as for the system dynamics. To also get rather accurate results in terms of stress fields within regions that are prone to fail upon high-g shocks, a correction factor is proposed by accounting for the local stress amplification induced by re-entrant corners.
Physically-based reduced order modelling of a uni-axial polysilicon MEMS accelerometer.
Ghisi, Aldo; Mariani, Stefano; Corigliano, Alberto; Zerbini, Sarah
2012-10-17
In this paper, the mechanical response of a commercial off-the-shelf, uni-axial polysilicon MEMS accelerometer subject to drops is numerically investigated. To speed up the calculations, a simplified physically-based (beams and plate), two degrees of freedom model of the movable parts of the sensor is adopted. The capability and the accuracy of the model are assessed against three-dimensional finite element simulations, and against outcomes of experiments on instrumented samples. It is shown that the reduced order model provides accurate outcomes as for the system dynamics. To also get rather accurate results in terms of stress fields within regions that are prone to fail upon high-g shocks, a correction factor is proposed by accounting for the local stress amplification induced by re-entrant corners.
A Comparison of Reduced Order Modeling Techniques Used in Dynamic Substructuring [PowerPoint
Roettgen, Dan [Wisc; Seeger, Benjamin [Stuttgart; Tai, Wei Che [Washington; Baek, Seunghun [Michigan; Dossogne, Tilan [Liege; Allen, Matthew S [Wisc; Kuether, Robert J.; Brake, Matthew Robert; Mayes, Randall L.
2016-01-01
Experimental dynamic substructuring is a means whereby a mathematical model for a substructure can be obtained experimentally and then coupled to a model for the rest of the assembly to predict the response. Recently, various methods have been proposed that use a transmission simulator to overcome sensitivity to measurement errors and to exercise the interface between the substructures; including the Craig-Bampton, Dual Craig-Bampton, and Craig-Mayes methods. This work compares the advantages and disadvantages of these reduced order modeling strategies for two dynamic substructuring problems. The methods are first used on an analytical beam model to validate the methodologies. Then they are used to obtain an experimental model for structure consisting of a cylinder with several components inside connected to the outside case by foam with uncertain properties. This represents an exceedingly difficult structure to model and so experimental substructuring could be an attractive way to obtain a model of the system.
Fast and efficient evaluation of gravitational waveforms via reduced-order spline interpolation
Galley, Chad R
2016-01-01
Numerical simulations of merging black hole binaries produce the most accurate gravitational waveforms. The availability of hundreds of these numerical relativity (NR) waveforms, often containing many higher spherical harmonic modes, allows one to study many aspects of gravitational waves. Amongst these are the response of data analysis pipelines, the calibration of semi-analytical models, the building of reduced-order surrogates, the estimation of the parameters of detected gravitational waves, and the composition of public catalogs of NR waveform data. The large number of generated NR waveforms consequently requires efficient data storage and handling, especially since many more waveforms will be generated at an increased rate in the forthcoming years. In addition, gravitational wave data analyses often require the NR waveforms to be interpolated and uniformly resampled at high sampling rates. Previously, this resulted in very large data files (up to $\\sim$ several GB) in memory-intensive operations, which ...
Reduced-order Abraham-Lorentz-Dirac equation and the consistency of classical electromagnetism
Steane, Andrew M
2014-01-01
It is widely believed that classical electromagnetism is either unphysical or inconsistent, owing to pathological behaviour when self-force and radiation reaction are non-negligible. We argue that there is no inconsistency as long as it is recognized that certain types of charge distribution are simply impossible, such as, for example, a point particle with finite charge and finite inertia. This is owing to the fact that negative inertial mass is an unphysical concept in classical physics. It remains useful to obtain an equation of motion for small charged objects that describes their motion to good approximation without requiring knowledge of the charge distribution within the object. We give a simple method to achieve this, leading to a reduced-order form of the Abraham-Lorentz-Dirac equation, essentially as proposed by Eliezer, Landau and Lifshitz.
Cluster-based reduced-order modelling of a mixing layer
Kaiser, Eurika; Cordier, Laurent; Spohn, Andreas; Segond, Marc; Abel, Markus; Daviller, Guillaume; Niven, Robert K
2013-01-01
We propose a novel cluster-based reduced-order modelling (CROM) strategy of unsteady flows. CROM builds on the pioneering works of Gunzburger's group in cluster analysis (Burkardt et al. 2006) and Eckhardt's group in transition matrix models (Schneider et al. 2007) and constitutes a potential alternative to POD models. This strategy processes a time-resolved sequence of flow snapshots in two steps. First, the snapshot data is clustered into a small number of representative states, called centroids, in the state space. These centroids partition the state space in complementary non-overlapping regions (centroidal Voronoi cells). Departing from the standard algorithm, the probability of the clusters are determined, and the states are sorted by transition matrix consideration. Secondly, the transitions between the states are dynamically modelled via a Markov process. Physical mechanisms are then distilled by a refined analysis of the Markov process, e.g. with the finite-time Lyapunov exponent and entropic methods...
Mudunuru, M K; Harp, D R; Guthrie, G D; Viswanathan, H S
2016-01-01
The goal of this paper is to assess the utility of Reduced-Order Models (ROMs) developed from 3D physics-based models for predicting transient thermal power output for an enhanced geothermal reservoir while explicitly accounting for uncertainties in the subsurface system and site-specific details. Numerical simulations are performed based on Latin Hypercube Sampling (LHS) of model inputs drawn from uniform probability distributions. Key sensitive parameters are identified from these simulations, which are fracture zone permeability, well/skin factor, bottom hole pressure, and injection flow rate. The inputs for ROMs are based on these key sensitive parameters. The ROMs are then used to evaluate the influence of subsurface attributes on thermal power production curves. The resulting ROMs are compared with field-data and the detailed physics-based numerical simulations. We propose three different ROMs with different levels of model parsimony, each describing key and essential features of the power production cu...
Maes, K.; Lourens, E.; Van Nimmen, K.; Reynders, E.; De Roeck, G.; Lombaert, G.
2015-02-01
In structural dynamics, the forces acting on a structure are often not well known. System inversion techniques may be used to estimate these forces from the measured response of the structure. This paper first derives conditions for the invertibility of linear system models that apply to any instantaneous input estimation or joint input-state estimation algorithm. The conditions ensure the identifiability of the dynamic forces and system states, their stability and uniqueness. The present paper considers the specific case of modally reduced order models, which are generally obtained from a physical, finite element model, or from experimental data. It is shown how in this case the conditions can be directly expressed in terms of the modal properties of the structure. A distinction is made between input estimation and joint input-state estimation. Each of the conditions is illustrated by a conceptual example. The practical implementation is discussed for a case study where a sensor network for a footbridge is designed.
Cherabi, Bilal; Hamrani, Abderrachid; Belaidi, Idir; Khelladi, Sofiane; Bakir, Farid
2016-10-01
In the present work, a reduced-order method, "Proper Generalized Decomposition (PGD)" is extended and applied to the resolution of the Reynolds equation describing the behavior of the lubricant in hydrodynamic journal bearing. The PGD model is employed to solve the characteristic 'Reynolds' partial differential equation using the separation technique through the alternating direction strategy. The resulting separated-dimension system has a low computation cost compared to classical finite-difference resolution. Several numerical benchmark examples are investigated to verify the validity and accuracy of the proposed method. It has been found that numerical results obtained by the PGD method can achieve an improved convergence rate with a very low computation cost.
How can we strengthen students’ social relations in order to reduce school dropout?
Ingholt, Liselotte; Sørensen, Betina Bang; Andersen, Susan
2015-01-01
BACKGROUND: This article describes the rationale and contents of an intervention program aimed at strengthening students' social relations in order to reduce dropout from vocational schools in Denmark. Taking its theoretical cue from the concept of 'social participation', a qualitative study...... on ethnographic methods, including 22 qualitative interviews with students 17-19 years old and fieldwork with participant observations at four vocational schools over 40 days, including informal interviews and discussion meetings with managers, teachers, counselors and students. As part of the fieldwork, four...... additional qualitative interviews and four group interviews were conducted with students 16-25 years old. RESULTS: The qualitative data collection resulted in seven major themes to be addressed in the intervention: social relations, sole focus on professional skills, institutionalized individualization...
A Comparison of Reduced Order Modeling Techniques Used in Dynamic Substructuring.
Roettgen, Dan; Seegar, Ben; Tai, Wei Che; Baek, Seunghun; Dossogne, Tilan; Allen, Matthew; Kuether, Robert J.; Brake, Matthew Robert; Mayes, Randall L.
2015-10-01
Experimental dynamic substructuring is a means whereby a mathematical model for a substructure can be obtained experimentally and then coupled to a model for the rest of the assembly to predict the response. Recently, various methods have been proposed that use a transmission simulator to overcome sensitivity to measurement errors and to exercise the interface between the substructures; including the Craig-Bampton, Dual Craig-Bampton, and Craig-Mayes methods. This work compares the advantages and disadvantages of these reduced order modeling strategies for two dynamic substructuring problems. The methods are first used on an analytical beam model to validate the methodologies. Then they are used to obtain an experimental model for structure consisting of a cylinder with several components inside connected to the outside case by foam with uncertain properties. This represents an exceedingly difficult structure to model and so experimental substructuring could be an attractive way to obtain a model of the system.
Suarez-Antola, Roberto, E-mail: roberto.suarez@miem.gub.u, E-mail: rsuarez@ucu.edu.u [Universidad Catolica del Uruguay, Montevideo (Uruguay). Fac. de Ingenieria y Tecnologias. Dept. de Matematica; Ministerio de Industria, Energia y Mineria, Montevideo (Uruguay). Direccion General de Secretaria
2011-07-01
One of the goals of nuclear power systems design and operation is to restrict the possible states of certain critical subsystems to remain inside a certain bounded set of admissible states and state variations. In the framework of an analytic or numerical modeling process of a BWR power plant, this could imply first to find a suitable approximation to the solution manifold of the differential equations describing the stability behavior, and then a classification of the different solution types concerning their relation with the operational safety of the power plant. Inertial manifold theory gives a foundation for the construction and use of reduced order models (ROM's) of reactor dynamics to discover and characterize meaningful bifurcations that may pass unnoticed during digital simulations done with full scale computer codes of the nuclear power plant. The March-Leuba's BWR ROM is generalized and used to exemplify the analytical approach developed here. A nonlinear integral-differential equation in the logarithmic power is derived. Introducing a KBM Ansatz, a coupled set of two nonlinear ordinary differential equations is obtained. Analytical formulae are derived for the frequency of oscillation and the parameters that determine the stability of the steady states, including sub- and supercritical PAH bifurcations. A Bautin's bifurcation scenario seems possible on the power-flow plane: near the boundary of stability, a region where stable steady states are surrounded by unstable limit cycles surrounded at their turn by stable limit cycles. The analytical results are compared with recent digital simulations and applications of semi-analytical bifurcation theory done with reduced order models of BWR. (author)
San, Omer
2014-01-01
In this paper, a stabilized proper orthogonal decomposition (POD) reduced-order model (ROM) is presented for the barotropic vorticity equation. We apply the POD-ROM model to mid-latitude simplified oceanic basins, which are standard prototypes of more realistic large-scale ocean dynamics. A mode dependent eddy viscosity closure scheme is used to model the effects of the discarded POD modes. A sensitivity analysis with respect to the free eddy viscosity stabilization parameter is performed for various POD-ROMs with different numbers of POD modes. The POD-ROM results are validated against the Munk layer resolving direct numerical simulations using a fully conservative fourth-order Arakawa scheme. A comparison with the standard Galerkin POD-ROM without any stabilization is also included in our investigation. Significant improvements in the accuracy over the standard Galerkin model are shown for a four-gyre ocean circulation problem. This first step in the numerical assessment of the POD-ROM shows that it could r...
A reduced-order model from high-dimensional frictional hysteresis.
Biswas, Saurabh; Chatterjee, Anindya
2014-06-08
Hysteresis in material behaviour includes both signum nonlinearities as well as high dimensionality. Available models for component-level hysteretic behaviour are empirical. Here, we derive a low-order model for rate-independent hysteresis from a high-dimensional massless frictional system. The original system, being given in terms of signs of velocities, is first solved incrementally using a linear complementarity problem formulation. From this numerical solution, to develop a reduced-order model, basis vectors are chosen using the singular value decomposition. The slip direction in generalized coordinates is identified as the minimizer of a dissipation-related function. That function includes terms for frictional dissipation through signum nonlinearities at many friction sites. Luckily, it allows a convenient analytical approximation. Upon solution of the approximated minimization problem, the slip direction is found. A final evolution equation for a few states is then obtained that gives a good match with the full solution. The model obtained here may lead to new insights into hysteresis as well as better empirical modelling thereof.
Schröder, Markus; Schreiber, Michael; Kleinekathöfer, Ulrich
2007-03-21
Several techniques to solve a hierarchical set of equations of motion for propagating a reduced density matrix coupled to a thermal bath have been developed in recent years. This is either done using the path integral technique as in the original proposal by Tanimura and Kubo [J. Phys. Soc. Jpn. 58, 101 (1998)] or by the use of stochastic fields as done by Yan et al. [Chem. Phys. Lett. 395, 216 (2004)]. Based on the latter ansatz a compact derivation of the hierarchy using a decomposition of the spectral density function is given in the present contribution. The method is applied to calculate the time evolution of the reduced density matrix describing the motion in a harmonic, an anharmonic, and two coupled oscillators where each system is coupled to a thermal bath. Calculations to several orders in the system-bath coupling with two different truncations of the hierarchy are performed. The respective density matrices are used to calculate the time evolution of various system properties and the results are compared and discussed with a special focus on the convergence with respect to the truncation scheme applied.
Clauser, Johanna; Gester, Kathrin; Roggenkamp, Jan; Mager, Ilona; Maas, Judith; Jansen, Sebastian V; Steinseifer, Ulrich
2014-01-01
In the development of new hemocompatible biomaterials, surface modification appears to be a suitable method in order to reduce the thrombogenetic potential of such materials. In this study, polycarbonate-urethane (PCU) tubes with different surface microstructures to be used for aortic heart valve models were investigated with regard to the thrombogenicity. The surface structures were produced by using a centrifugal casting process for manufacturing PCU tubes with defined casting mold surfaces which are conferred to the PCU surface during the process. Tubes with different structures defined by altering groove widths were cut into films and investigated under dynamic flow conditions in contact with porcine blood. The analysis was carried out by laser scanning microscopy which allowed for counting various morphological types of platelets with regard to the grade of activation. The comparison between plain and shaped PCU samples showed that the surface topography led to a decline of the activation of the coagulation cascade and thus to the reduction of the fibrin synthesis. Comparing different types of structures revealed that smooth structures with a small groove width (d ~ 3 μm) showed less platelet activation as well as less adhesion in contrast to a distinct wave structure (d ~ 90 μm). These results prove surface modification of polymer biomaterials to be a suitable method for reducing thrombogenicity and hence give reason for further alterations and improvements.
Chen, Xin; Liu, Li; Zhou, Sida; Yue, Zhenjiang
2016-09-01
Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.
Markov chain order estimation with parametric significance tests of conditional mutual information
Papapetrou, Maria
2015-01-01
Besides the different approaches suggested in the literature, accurate estimation of the order of a Markov chain from a given symbol sequence is an open issue, especially when the order is moderately large. Here, parametric significance tests of conditional mutual information (CMI) of increasing order $m$, $I_c(m)$, on a symbol sequence are conducted for increasing orders $m$ in order to estimate the true order $L$ of the underlying Markov chain. CMI of order $m$ is the mutual information of two variables in the Markov chain being $m$ time steps apart, conditioning on the intermediate variables of the chain. The null distribution of CMI is approximated with a normal and gamma distribution deriving analytic expressions of their parameters, and a gamma distribution deriving its parameters from the mean and variance of the normal distribution. The accuracy of order estimation is assessed with the three parametric tests, and the parametric tests are compared to the randomization significance test and other known ...
Reduced enrichment for research and test reactors: Proceedings
1988-05-01
The international effort to develop new research reactor fuel materials and designs based on the use of low-enriched uranium, instead of highly-enriched uranium, has made much progress during the eight years since its inception. To foster direct communication and exchange of ideas among the specialist in this area, the Reduced Enrichment Research and Test Reactor (RERTR) Program, at the Argonne National Laboratory, sponsored this meeting as the ninth of a series which began in 1978. All previous meetings of this series are listed on the facing page. The focus of this meeting was on the LEU fuel demonstration which was in progress at the Oak Ridge Research (ORR) reactor, not far from where the meeting was held. The visit to the ORR, where a silicide LEU fuel with 4.8 g A/cm/sup 3/ was by then in routine use, illustrated how far work has progressed.
Niu, Ran; Skliar, Mikhail
2012-07-01
In this paper, we develop and validate a method to identify computationally efficient site- and patient-specific models of ultrasound thermal therapies from MR thermal images. The models of the specific absorption rate of the transduced energy and the temperature response of the therapy target are identified in the reduced basis of proper orthogonal decomposition of thermal images, acquired in response to a mild thermal test excitation. The method permits dynamic reidentification of the treatment models during the therapy by recursively utilizing newly acquired images. Such adaptation is particularly important during high-temperature therapies, which are known to substantially and rapidly change tissue properties and blood perfusion. The developed theory was validated for the case of focused ultrasound heating of a tissue phantom. The experimental and computational results indicate that the developed approach produces accurate low-dimensional treatment models despite temporal and spatial noises in MR images and slow image acquisition rate.
Linear and nonlinear stability analysis in BWRs applying a reduced order model
Olvera G, O. A.; Espinosa P, G.; Prieto G, A., E-mail: omar_olverag@hotmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, 09340 Ciudad de Mexico (Mexico)
2016-09-15
Boiling Water Reactor (BWR) stability studies are generally conducted through nonlinear reduced order models (Rom) employing various techniques such as bifurcation analysis and time domain numerical integration. One of those models used for these studies is the March-Leuba Rom. Such model represents qualitatively the dynamic behavior of a BWR through a one-point reactor kinetics, a one node representation of the heat transfer process in fuel, and a two node representation of the channel Thermal hydraulics to account for the void reactivity feedback. Here, we study the effect of this higher order model on the overall stability of the BWR. The change in the stability boundaries is determined by evaluating the eigenvalues of the Jacobian matrix. The nonlinear model is also integrated numerically to show that in the nonlinear region, the system evolves to stable limit cycles when operating close to the stability boundary. We also applied a new technique based on the Empirical Mode Decomposition (Emd) to estimate a parameter linked with stability in a BWR. This instability parameter is not exactly the classical Decay Ratio (Dr), but it will be linked with it. The proposed method allows decomposing the analyzed signal in different levels or mono-component functions known as intrinsic mode functions (Imf). One or more of these different modes can be associated to the instability problem in BWRs. By tracking the instantaneous frequencies (calculated through Hilbert Huang Transform (HHT) and the autocorrelation function (Acf) of the Imf linked to instability. The estimation of the proposed parameter can be achieved. The current methodology was validated with simulated signals of the studied model. (Author)
Calibration of aero-structural reduced order models using full-field experimental measurements
Perez, R.; Bartram, G.; Beberniss, T.; Wiebe, R.; Spottswood, S. M.
2017-03-01
The structural response of hypersonic aircraft panels is a multi-disciplinary problem, where the nonlinear structural dynamics, aerodynamics, and heat transfer models are coupled. A clear understanding of the impact of high-speed flow effects on the structural response, and the potential influence of the structure on the local environment, is needed in order to prevent the design of overly-conservative structures, a common problem in past hypersonic programs. The current work investigates these challenges from a structures perspective. To this end, the first part of this investigation looks at the modeling of the response of a rectangular panel to an external heating source (thermo-structural coupling) where the temperature effect on the structure is obtained from forward looking infrared (FLIR) measurements and the displacement via 3D-digital image correlation (DIC). The second part of the study uses data from a previous series of wind-tunnel experiments, performed to investigate the response of a compliant panel to the effects of high-speed flow, to train a pressure surrogate model. In this case, the panel aero-loading is obtained from fast-response pressure sensitive paint (PSP) measurements, both directly and from the pressure surrogate model. The result of this investigation is the use of full-field experimental measurements to update the structural model and train a computational efficient model of the loading environment. The use of reduced order models, informed by these full-field physical measurements, is a significant step toward the development of accurate simulation models of complex structures that are computationally tractable.
Numerical simulation and reduced-order modeling of a flapping airfoil
Lewin, Gregory Carl
Recent advances in many fields have made the design of micro-aerial vehicles that implement flapping wings a possibility. However, there are many outstanding problems that must be solved before flapping flight can be implemented as a practical means of propulsion. This dissertation focuses on two important aspects of flapping flight: the physics of the flow of a fluid around a heaving airfoil and the development of a reduced-order model for the control of a flapping airfoil. To study the physics of the flow, a numerical model for two-dimensional flow around an airfoil undergoing prescribed oscillatory motions in a viscous flow is developed. The model is used to examine the flow characteristics and power coefficients of a symmetric airfoil heaving sinusoidally over a range of frequencies and amplitudes. Both periodic and aperiodic solutions are found. Additionally, some flows are asymmetric in that the up-stroke is not a mirror image of the down-stroke. For a given Strouhal number---defined as the product of dimensionless frequency and heave amplitude---the maximum efficiency occurs at an intermediate heaving frequency. This is in contrast to ideal flow models, in which efficiency increases monotonically as frequency decreases. Below a threshold frequency, the separation of the leading edge vortices early in each stroke reduces the force on the airfoil and leads to diminished thrust and efficiency. Above the optimum frequency, the efficiency decreases similarly to inviscid theory. For most cases, the efficiency can be correlated to interactions between leading and trailing edge vortices, with positive reinforcement leading to relatively high efficiency, and negative reinforcement leading to relatively low efficiency. Additionally, the efficiency is related to the proximity of the heaving frequency to the frequency of the most spatially unstable mode of the average velocity profile of the wake; the greatest efficiency occurs when the two frequencies are nearly
Prill, Dennis; Class, Andreas G. [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). AREVA Nuclear Professional School (ANPS)
2013-07-01
Unexpected non-linear boiling water reactor (BWR) instability events in various plants, e.g. LaSalle II in 1988 and Oskarshamn II in 1990 amongst others, emphasize the major safety relevance and the existence of parameter regions with unstable behavior. A detailed description of the complete dynamical non-linear behavior is of paramount importance for BWR operation. An extension of state-of-the-art methodology towards a more general stability description, also applicable in the non-linear region, could lead to a deeper understanding of non-linear BWR stability phenomena. With the intention of a full non-linear stability analysis of the two-phase BWR system, the present paper aims at a general non-linear methodology capable to achieve reliable and numerical stable reduced order models (ROMs), representing the dynamical behavior of an original system based on a small number of transients. Model-specific options and aspects of the proposed methodology are focused on and illustrated by means of a strongly non-linear dynamical system showing complex oscillating behavior. Prediction capability of the proposed methodology is also addressed. (orig.)
LQG controller designs from reduced order models for a launch vehicle
Ashwin Dhabale; R N Banavar; M V Dhekane
2008-02-01
The suppression of liquid fuel slosh motion is critical in a launch vehicle (LV). In particular, during certain stages of the launch, the dynamics of the fuel interacts adversely with the rigid body dynamics of the LV and the feedback controller must attentuate these effects. This paper describes the effort of a multivariable control approach applied to the Geosynchronous Satellite Launch Vehicle (GSLV) of the Indian Space Research Organization (ISRO) during a certain stage of its launch. The fuel slosh dynamics are modelled using a pendulum model analogy. We describe two design methodologies using the Linear-Quadratic Gaussian (LQG) technique. The novelty of the technique is that we apply the LQG design for models that are reduced in order through inspection alone. This is possible from a perspective that the LV could be viewed as many small systems attached to a main body and the interactions of some of these smaller systems could be neglected at the controller design stage provided sufﬁcient robustness is ensured by the controller. The ﬁrst LQG design is carried out without the actuator dynamics incorporated at the design stage and for the second design we neglect the slosh dynamics as well.
Frequency domain reduced order models for gravitational waves from aligned-spin black-hole binaries
Pürrer, Michael
2014-01-01
Black-hole binary coalescences are one of the most promising sources for the first detection of gravitational waves. Fast and accurate theoretical models of the gravitational radiation emitted from these coalescences are highly important for the detection and extraction of physical parameters. Spinning effective-one-body (EOB) models for binaries with aligned spins have been shown to be highly faithful, but are slow to generate and thus have not yet been used for parameter estimation studies. I provide a frequency-domain singular value decomposition (SVD)-based surrogate reduced order model that is thousands to hundred thousands times faster for typical system masses and has a faithfulness mismatch of better than $\\sim 0.1\\%$ with the original SEOBNRv1 model for advanced LIGO detectors. This model enables parameter estimation studies up to signal-to-noise ratios (SNRs) of 20 and even up to SNR 50 for masses below $50 M_\\odot$. This article discusses various choices for approximations and interpolation over th...
Reduced-order prediction of rogue waves in two-dimensional deep-water waves
Farazmand, Mohammad; Sapsis, Themistoklis P.
2017-07-01
We consider the problem of large wave prediction in two-dimensional water waves. Such waves form due to the synergistic effect of dispersive mixing of smaller wave groups and the action of localized nonlinear wave interactions that leads to focusing. Instead of a direct simulation approach, we rely on the decomposition of the wave field into a discrete set of localized wave groups with optimal length scales and amplitudes. Due to the short-term character of the prediction, these wave groups do not interact and therefore their dynamics can be characterized individually. Using direct numerical simulations of the governing envelope equations we precompute the expected maximum elevation for each of those wave groups. The combination of the wave field decomposition algorithm, which provides information about the statistics of the system, and the precomputed map for the expected wave group elevation, which encodes dynamical information, allows (i) for understanding of how the probability of occurrence of rogue waves changes as the spectrum parameters vary, (ii) the computation of a critical length scale characterizing wave groups with high probability of evolving to rogue waves, and (iii) the formulation of a robust and parsimonious reduced-order prediction scheme for large waves. We assess the validity of this scheme in several cases of ocean wave spectra.
Giovanni Capellari
2015-12-01
Full Text Available Health monitoring of lightweight structures, like thin flexible plates, is of interest in several engineering fields. In this paper, a recursive Bayesian procedure is proposed to monitor the health of such structures through data collected by a network of optimally placed inertial sensors. As a main drawback of standard monitoring procedures is linked to the computational costs, two remedies are jointly considered: first, an order-reduction of the numerical model used to track the structural dynamics, enforced with proper orthogonal decomposition; and, second, an improved particle filter, which features an extended Kalman updating of each evolving particle before the resampling stage. The former remedy can reduce the number of effective degrees-of-freedom of the structural model to a few only (depending on the excitation, whereas the latter one allows to track the evolution of damage and to locate it thanks to an intricate formulation. To assess the effectiveness of the proposed procedure, the case of a plate subject to bending is investigated; it is shown that, when the procedure is appropriately fed by measurements, damage is efficiently and accurately estimated.
Shanthi, C; Rao, K P
1997-01-01
Calcification limits the functional lifetime of cardiac valve substitutes fabricated from glutaraldehyde preserved bovine pericardium. Host factors, mainly younger age, and implant factors, mainly glutaraldehyde cross-linking, are implicated in the calcification process. Glutaraldehyde cross-linking is believed to activate the potential sites in the tissues for biocalcification. In the present work, we investigated the possibility of using alginate azide (AA) instead of glutaraldehyde for the preservation of pericardial tissues in order to enhance the durability of bioprosthetic heart valves. Grafting with poly(GMA-BA) copolymer to the alginate azide cross-linked pericardial (AACPC) tissue was carried out to obtain better stability, strength, and anticalcification properties. The strength property and thermal stability of the AA cross-linked tissues were studied. Calcification studies in rat subdermal models reveal that AA cross-linking reduces the calcification to negligible levels. After 30 days implantation, the calcium content was found to be 10.4 +/- 1.2 and 6.1 +/- 0.3 micrograms mg-1 for untreated AACPC and polymer grafted AACPC, respectively, compared to a value of 100 +/- 1.2 micrograms mg-1 calcium recorded for control glutaraldehyde cross-linked pericardial (GCPC) tissues.
Effect of reduction time on third order optical nonlinearity of reduced graphene oxide
Sreeja, V. G.; Vinitha, G.; Reshmi, R.; Anila, E. I.; Jayaraj, M. K.
2017-04-01
We report the influence of reduction time on structural, linear and nonlinear optical properties of reduced graphene oxide (rGO) thin films synthesized by spin coating method. We observed that the structural, linear and nonlinear optical properties can be tuned with reduction time in GO is due to the increased structural ordering because of the restoration of sp2 carbon atoms with the time of reduction. The nonlinear absorption studies by open aperture Z-scan technique exhibited a saturable absorption. The nonlinear refraction studies showed the self de focusing nature of rGO by closed aperture Z scan technique. The nonlinear absorption coefficient and saturation intensity varies with the time for reduction of GO which is attributed to the depletion of valence band and the conduction band filling effect. Our results emphasize duration for reduction of GO dependent optical nonlinearity of rGO thin films to a great extent and explore its applications Q switched mode locking laser systems for generating ultra short laser pulses and in optical sensors. The rGO coated films were characterized by X-Ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis absorption spectroscopy (UV-Vis), Photoluminescence (PL) and Scanning electron microscope (SEM) measurements.
A three-dimensional nonlinear reduced-order predictive joint model
无
2003-01-01
Mechanical joints can have significant effects on the dynamics of assembled structures. However, the lack of efficacious predictive dynamic models for joints hinders accurate prediction of their dynamic behavior. The goal of our work is to develop physics-based, reduced-order, finite element models that are capable of replicating the effects of joints on vibrating structures. The authors recently developed the so-called two-dimensional adjusted Iwan beam element (2-D AIBE) to simulate the hysteretic behavior of bolted joints in 2-D beam structures. In this paper, 2-D AIBE is extended to three-dimensional cases by formulating a three-dimensional adjusted Iwan beam element (3-D AIBE). Impulsive loading experiments are applied to a jointed frame structure and a beam structure containing the same joint. The frame is subjected to excitation out of plane so that the joint is under rotation and single axis bending. By assuming that the rotation in the joint is linear elastic, the parameters of the joint associated with bending in the frame are identified from acceleration responses of the jointed beam structure, using a multi-layer feed-forward neural network (MLFF). Numerical simulation is then performed on the frame structure using the identified parameters. The good agreement between the simulated and experimental impulsive acceleration responses of the frame structure validates the efficacy of the presented 3-D AIBE, and indicates that the model can potentially be applied to more complex structural systems with joint parameters identified from a relatively simple structure.
Capellari, Giovanni; Azam, Saeed Eftekhar; Mariani, Stefano
2015-12-22
Health monitoring of lightweight structures, like thin flexible plates, is of interest in several engineering fields. In this paper, a recursive Bayesian procedure is proposed to monitor the health of such structures through data collected by a network of optimally placed inertial sensors. As a main drawback of standard monitoring procedures is linked to the computational costs, two remedies are jointly considered: first, an order-reduction of the numerical model used to track the structural dynamics, enforced with proper orthogonal decomposition; and, second, an improved particle filter, which features an extended Kalman updating of each evolving particle before the resampling stage. The former remedy can reduce the number of effective degrees-of-freedom of the structural model to a few only (depending on the excitation), whereas the latter one allows to track the evolution of damage and to locate it thanks to an intricate formulation. To assess the effectiveness of the proposed procedure, the case of a plate subject to bending is investigated; it is shown that, when the procedure is appropriately fed by measurements, damage is efficiently and accurately estimated.
Jiao, Xiaohong; Mei, Zhisong
2010-10-01
To improve the quality of strip thickness, synchronisation control is investigated for cold rolling mills driven by dual-cylinder electro-hydraulic servo systems. Realising synchronised control in hydraulic automatic gauge control (HAGC) systems of cold rolling mills has challenges with not only the inherent nonlinearities of hydraulic servo systems and uncertainties of load variation but also measurement delay of strip thickness. Since all states are not measurable in practice, output feedback robust synchronisation control problem should be addressed for uncertain nonlinear systems with output delay. Thus, a reduced-order observer-based robust synchronous controller is presented by employing Lyapunov functional stability theory. The controller designed by incorporating the integral of the position synchronisation error of two pistons into state variables successfully guarantees asymptotic convergence to zero of both tracking errors and synchronisation error simultaneously regardless of the nonlinearities and uncertainties as well as the measurement delay. Simulation results in a model obtained from a real cold strip rolling mill demonstrate the effectiveness of the approach.
A Reduced Order Model for the Design of Oxy-Coal Combustion Systems
Steven L. Rowan
2015-01-01
Full Text Available Oxy-coal combustion is one of the more promising technologies currently under development for addressing the issues associated with greenhouse gas emissions from coal-fired power plants. Oxy-coal combustion involves combusting the coal fuel in mixtures of pure oxygen and recycled flue gas (RFG consisting of mainly carbon dioxide (CO2. As a consequence, many researchers and power plant designers have turned to CFD simulations for the study and design of new oxy-coal combustion power plants, as well as refitting existing air-coal combustion facilities to oxy-coal combustion operations. While CFD is a powerful tool that can provide a vast amount of information, the simulations themselves can be quite expensive in terms of computational resources and time investment. As a remedy, a reduced order model (ROM for oxy-coal combustion has been developed to supplement the CFD simulations. With this model, it is possible to quickly estimate the average outlet temperature of combustion flue gases given a known set of mass flow rates of fuel and oxidant entering the power plant boiler as well as determine the required reactor inlet mass flow rates for a desired outlet temperature. Several cases have been examined with this model. The results compare quite favorably to full CFD simulation results.
Hsu, Louis M.
1979-01-01
A comparison of the relative ordering power of separate and grouped-items true-false tests indicated that neither type of test was uniformly superior to the other across all levels of knowledge of examinees. Grouped-item tests were found superior for examinees with low levels of knowledge. (Author/CTM)
An Analysis of Higher-Order Thinking on Algebra I End-of-Course Tests
Thompson, Tony
2011-01-01
This research provides insight into one US state's effort to incorporate higher-order thinking on its Algebra I End-of-Course tests. To facilitate the inclusion of higher-order thinking, the state used "Dimensions of Thinking" (Marzano et al., 1988) and "Bloom's Taxonomy" (Bloom et al., 1956). An analysis of Algebra I test items found that the…
A reduced order model based on Kalman filtering for sequential data assimilation of turbulent flows
Meldi, M.; Poux, A.
2017-10-01
A Kalman filter based sequential estimator is presented in this work. The estimator is integrated in the structure of segregated solvers for the analysis of incompressible flows. This technique provides an augmented flow state integrating available observation in the CFD model, naturally preserving a zero-divergence condition for the velocity field. Because of the prohibitive costs associated with a complete Kalman Filter application, two model reduction strategies have been proposed and assessed. These strategies dramatically reduce the increase in computational costs of the model, which can be quantified in an augmentation of 10%- 15% with respect to the classical numerical simulation. In addition, an extended analysis of the behavior of the numerical model covariance Q has been performed. Optimized values are strongly linked to the truncation error of the discretization procedure. The estimator has been applied to the analysis of a number of test cases exhibiting increasing complexity, including turbulent flow configurations. The results show that the augmented flow successfully improves the prediction of the physical quantities investigated, even when the observation is provided in a limited region of the physical domain. In addition, the present work suggests that these Data Assimilation techniques, which are at an embryonic stage of development in CFD, may have the potential to be pushed even further using the augmented prediction as a powerful tool for the optimization of the free parameters in the numerical simulation.
An Efficient Reduced-Order Model for the Nonlinear Dynamics of Carbon Nanotubes
Xu, Tiantian
2014-08-17
Because of the inherent nonlinearities involving the behavior of CNTs when excited by electrostatic forces, modeling and simulating their behavior is challenging. The complicated form of the electrostatic force describing the interaction of their cylindrical shape, forming upper electrodes, to lower electrodes poises serious computational challenges. This presents an obstacle against applying and using several nonlinear dynamics tools that typically used to analyze the behavior of complicated nonlinear systems, such as shooting, continuation, and integrity analysis techniques. This works presents an attempt to resolve this issue. We present an investigation of the nonlinear dynamics of carbon nanotubes when actuated by large electrostatic forces. We study expanding the complicated form of the electrostatic force into enough number of terms of the Taylor series. We plot and compare the expanded form of the electrostatic force to the exact form and found that at least twenty terms are needed to capture accurately the strong nonlinear form of the force over the full range of motion. Then, we utilize this form along with an Euler–Bernoulli beam model to study the static and dynamic behavior of CNTs. The geometric nonlinearity and the nonlinear electrostatic force are considered. An efficient reduced-order model (ROM) based on the Galerkin method is developed and utilized to simulate the static and dynamic responses of the CNTs. We found that the use of the new expanded form of the electrostatic force enables avoiding the cumbersome evaluation of the spatial integrals involving the electrostatic force during the modal projection procedure in the Galerkin method, which needs to be done at every time step. Hence, the new method proves to be much more efficient computationally.
Simpson, Elizabeth C.
1989-01-01
Motion estimation is a field of great interest because of its many applications in areas such as robotics and image coding. The optic flow method is one such scheme which, although fairly accurate, is prone to error in the presence of noise. This thesis describes the use of the reduced order model Kalman filter (ROMKF) in reducing errors in displacement estimation due to degradation of the sequence. The implementation of filtering and motion estimation algorithms on the SUN workstation is also discussed. Results from preliminary testing were used to determine the degrees of freedom available for the ROMKF in the SUN software. The tests indicated that increasing the state to the left leads to slight improvement over the minimum state case. Therefore, the software uses the minimum model, with the option of adding states to the left only. The ROMKF was then used in conjunction with a hierarchical pel recursive motion estimation algorithm. Applying the ROMKF to the degraded displacements themselves generally yielded slight improvements in cases with noise degradation and noise plus blur. Filtering the images of the degraded sequence prior to motion estimation was less effective in these cases. Both methods performed badly in the case of blur alone, resulting in increased displacement errors. This is thought to be due in part to filter artifacts. Some improvements were obtained by varying the filter parameters when filtering the displacements directly. This result suggests that further study in varying filter parameters may lead to better results. The results of this thesis indicate that the ROMKF can play a part in reducing motion estimation errors from degraded sequences. However, more work needs to be done before the use of the ROMKF can be a practical solution.
2010-01-01
... employees about the safety risks associated with texting while driving. These initiatives should encourage... Leadership on Reducing Text Messaging While Driving 13513 Order 13513 Presidential Documents Executive Orders... Driving By the authority vested in me as President by the Constitution and the laws of the United...
Hu, Rui
2017-09-03
Mixing, thermal-stratification, and mass transport phenomena in large pools or enclosures play major roles for the safety of reactor systems. Depending on the fidelity requirement and computational resources, various modeling methods, from the 0-D perfect mixing model to 3-D Computational Fluid Dynamics (CFD) models, are available. Each is associated with its own advantages and shortcomings. It is very desirable to develop an advanced and efficient thermal mixing and stratification modeling capability embedded in a modern system analysis code to improve the accuracy of reactor safety analyses and to reduce modeling uncertainties. An advanced system analysis tool, SAM, is being developed at Argonne National Laboratory for advanced non-LWR reactor safety analysis. While SAM is being developed as a system-level modeling and simulation tool, a reduced-order three-dimensional module is under development to model the multi-dimensional flow and thermal mixing and stratification in large enclosures of reactor systems. This paper provides an overview of the three-dimensional finite element flow model in SAM, including the governing equations, stabilization scheme, and solution methods. Additionally, several verification and validation tests are presented, including lid-driven cavity flow, natural convection inside a cavity, laminar flow in a channel of parallel plates. Based on the comparisons with the analytical solutions and experimental results, it is demonstrated that the developed 3-D fluid model can perform very well for a wide range of flow problems.
Reducing the Need for Guesswork in Multiple-Choice Tests
Bush, Martin
2015-01-01
The humble multiple-choice test is very widely used within education at all levels, but its susceptibility to guesswork makes it a suboptimal assessment tool. The reliability of a multiple-choice test is partly governed by the number of items it contains; however, longer tests are more time consuming to take, and for some subject areas, it can be…
Nonlinear first order PDEs reducible to autonomous form polynomially homogeneous in the derivatives
Gorgone, Matteo; Oliveri, Francesco
2017-03-01
It is proved a theorem providing necessary and sufficient conditions enabling one to map a nonlinear system of first order partial differential equations, polynomial in the derivatives, to an equivalent autonomous first order system polynomially homogeneous in the derivatives. The result is intimately related to the symmetry properties of the source system, and the proof, involving the use of the canonical variables associated to the admitted Lie point symmetries, is constructive. First order Monge-Ampère systems, either with constant coefficients or with coefficients depending on the field variables, where the theorem can be successfully applied, are considered.
Motivating factors for physician ordering of factor V Leiden genetic tests.
Hindorff, Lucia A; Burke, Wylie; Laberge, Anne-Marie; Rice, Kenneth M; Lumley, Thomas; Leppig, Kathleen; Rosendaal, Frits R; Larson, Eric B; Psaty, Bruce M
2009-01-12
The factor V Leiden (FVL) genetic test is used by many physicians despite its uncertain clinical utility. We investigate whether self-reported motivations and behaviors concerning FVL genetic testing differ between 2 groups of primary care physicians defined by frequency of previous FVL test use. In January 2007, 112 physicians (60 frequent and 52 infrequent FVL test users) at Group Health, a large health care delivery system, were surveyed. Survey content areas included primary reasons and motivating factors for ordering the FVL test, the likelihood of ordering the FVL test for hypothetical patients, potential barriers to genetic testing, and practices and skills regarding FVL test ordering. Responses between groups agreed concerning most clinical- and patient-related factors. Frequent-FVL physicians were more likely than infrequent-FVL physicians to report ordering the FVL test for hypothetical patients with mesenteric venous thrombosis (adjusted odds ratio, 4.57; 95% confidence interval, 1.55-13.53) or venous thrombosis after hospital discharge (adjusted odds ratio, 3.42; 95% confidence interval, 1.30-8.95). Frequent-FVL physicians were also less likely to identify several items on the survey as barriers to genetic testing and were more likely to report high confidence in interpreting and explaining FVL test results. Generally, both physician groups reported similar motivating factors for ordering FVL tests, and reported behaviors were consistent with existing guidelines. More striking differences were observed for measures such as barriers to and confidence in using genetic tests. Although additional research is necessary to evaluate the impact of these results, they inform several knowledge-to-practice translation issues that are important for the successful integration of genetic testing into primary care.
Nonlinear AeroServoElastic Reduced Order Model for Active Structural Control Project
National Aeronautics and Space Administration — The overall goal of the proposed effort is to develop and demonstrate rigorous model order reduction (MOR) technologies to automatically generate fully coupled,...
Treatability Test Plan for an In Situ Biostimulation Reducing Barrier
Truex, Michael J.; Vermeul, Vince R.; Long, Philip E.; Brockman, Fred J.; Oostrom, Mart; Hubbard, Susan; Borden, Robert C.; Fruchter, Jonathan S.
2007-07-21
This treatability test plan supports a new, integrated strategy to accelerate cleanup of chromium in the Hanford 100 Areas. This plan includes performing a field-scale treatability test for bioreduction of chromate, nitrate, and dissolved oxygen. In addition to remediating a portion of the plume and demonstrating reduction of electron acceptors in the plume, the data from this test will be valuable for designing a full-scale bioremediation system to apply at this and other chromium plumes at Hanford.
The Careful Puppet Master: Reducing risk and fortifying acceptance testing with Jenkins CI
Smith, Jason A.; Richman, Gabriel; DeStefano, John; Pryor, James; Rao, Tejas; Strecker-Kellogg, William; Wong, Tony
2015-12-01
Centralized configuration management, including the use of automation tools such as Puppet, can greatly increase provisioning speed and efficiency when configuring new systems or making changes to existing systems, reduce duplication of work, and improve automated processes. However, centralized management also brings with it a level of inherent risk: a single change in just one file can quickly be pushed out to thousands of computers and, if that change is not properly and thoroughly tested and contains an error, could result in catastrophic damage to many services, potentially bringing an entire computer facility offline. Change management procedures can—and should—be formalized in order to prevent such accidents. However, like the configuration management process itself, if such procedures are not automated, they can be difficult to enforce strictly. Therefore, to reduce the risk of merging potentially harmful changes into our production Puppet environment, we have created an automated testing system, which includes the Jenkins CI tool, to manage our Puppet testing process. This system includes the proposed changes and runs Puppet on a pool of dozens of RedHat Enterprise Virtualization (RHEV) virtual machines (VMs) that replicate most of our important production services for the purpose of testing. This paper describes our automated test system and how it hooks into our production approval process for automatic acceptance testing. All pending changes that have been pushed to production must pass this validation process before they can be approved and merged into production.
Davijani, Nafiseh Zare; Jahanfarnia, Gholamreza; Abharian, Amir Esmaeili
2017-01-01
One of the most important issues with respect to nuclear reactors is power control. In this study, we designed a fractional-order sliding mode controller based on a nonlinear fractional-order model of the reactor system in order to track the reference power trajectory and overcome uncertainties and external disturbances. Since not all of the variables in an operating reactor are measurable or specified in the control law, we propose a reduced-order fractional neutron point kinetic (ROFNPK) model based on measurable variables. In the design, we assume the differences between the approximated model and the real system is limited. We use the obtained model in the controller design process and use the Lyapunov method to perform a stability analysis of the closed-loop system. We simulate the proposed reduced-order fractional-order sliding mode controller (ROFOSMC) using Matlab/Simulink, and its performance is compared with that of a reduced order integer-order sliding mode controller (ROIOSMC). Our simulation results indicate an acceptable performance of the proposed approach in tracking the reference power trajectory with respect to ROIOSMC because of faster response of control effort signal and the smaller tracking error. Moreover, the results illustrate the capability of the controller in rejection of the disturbance and the noise signals and the robustness of controller against uncertainty.
Konrad, Wilfried; Katul, Gabriel; Roth-Nebelsick, Anita; Grein, Michaela
2017-06-01
To address questions related to the acceleration or deceleration of the global hydrological cycle or links between the carbon and water cycles over land, reliable data for past climatic conditions based on proxies are required. In particular, the reconstruction of palaeoatmospheric CO2 content (Ca) is needed to assist the separation of natural from anthropogenic Ca variability and to explore phase relations between Ca and air temperature Ta time series. Both Ta and Ca are needed to fingerprint anthropogenic signatures in vapor pressure deficit, a major driver used to explain acceleration or deceleration phases in the global hydrological cycle. Current approaches to Ca reconstruction rely on a robust inverse correlation between measured stomatal density in leaves (ν) of many plant taxa and Ca. There are two methods that exploit this correlation: The first uses calibration curves obtained from extant species assumed to represent the fossil taxa, thereby restricting the suitable taxa to those existing today. The second is a hybrid eco-hydrological/physiological approach that determines Ca with the aid of systems of equations based on quasi-instantaneous leaf-gas exchange theories and fossil stomatal data collected along with other measured leaf anatomical traits and parameters. In this contribution, a reduced order model (ROM) is proposed that derives Ca from a single equation incorporating the aforementioned stomatal data, basic climate (e.g. temperature), estimated biochemical parameters of assimilation and isotope data. The usage of the ROM is then illustrated by applying it to isotopic and anatomical measurements from three extant species. The ROM derivation is based on a balance between the biochemical demand and atmospheric supply of CO2 that leads to an explicit expression linking stomatal conductance to internal CO2 concentration (Ci) and Ca. The resulting expression of stomatal conductance from the carbon economy of the leaf is then equated to another
2013-03-01
PhD (Member) Date AFIT-ENY-13-M-28 Abstract System identification has long been used as a tool for flight test engineers to char- acterize systems...under test ; however, the inputs to these characterization activities have previously been limited to wind tunnel and flight test data. There has been a...of the CCAC support personnel, and the help of AFIT Linux administrators. Further, I would like to thank Capt Cleaver . Sitting next to each other in
Innovative Development of Kernel-Based Reduced-Order Models for Predicting LCO Onset Project
National Aeronautics and Space Administration — Reducing uncertainty in the prediction of limit cycle oscillations (LCO) and other nonlinear aeroservoelastic phenomena is critical to flight safety. To do so...
In vitro vaccine potency testing: a proposal for reducing animal use for requalification testing.
Brown, K; Stokes, W
2012-01-01
This paper proposes a program under which the use of animals for requalification of in vitro potency tests could be eliminated. Standard References (USDA/CVB nomenclature) would be developed, characterized, stored and monitored by selected reference laboratories worldwide. These laboratories would employ scientists skilled in protein and glycoprotein chemistry and equipped with state-of-the-art instruments for required analyses. After Standard References are established, the reference laboratories would provide them to the animal health industry as "gold standards". Companies would then establish and validate a correlation between the Standard Reference and the company Master Reference (USDA/CVB nomenclature) using an internal in vitro assay. After this correlation is established, the company could use the Standard References for qualifying, monitoring and requalifying company Master References without the use of animals. Such a program would eliminate the need for animals for requalification of Master References and the need for each company to develop and validate a battery of Master Reference Monitoring assays. It would also provide advantages in terms of reduced costs and reduced time for requalification testing. As such it would provide a strong incentive for companies to develop and use in vitro assays for potency testing.
Reduced oxide soldering activation (ROSA) PWB solderability testing
Hernandez, C.L.; Hosking, F.M. [Sandia National Labs., Albuquerque, NM (United States). Physical and Joining Metallurgy Dept.; Reed, J. [Texas Instruments, Austin, TX (United States); Tench, D.M.; White, J. [Rockwell Science Center, Thousand Oaks, CA (United States)
1996-02-01
The effect of ROSA pretreatment on the solderability of environmentally stressed PWB test coupons was investigated. The PWB surface finish was an electroplated, reflowed solder. Test results demonstrated the ability to recover plated-through-hole fill of steam aged samples with solder after ROSA processing. ROSA offers an alternative method for restoring the solderability of aged PWB surfaces.
0-1 Test for Chaos in a Fractional Order Financial System with Investment Incentive
Baogui Xin
2013-01-01
weighted integral thought, the fractional order derivative's economics meaning is given. The 0-1 test algorithm and the improved Adams-Bashforth-Moulton predictor-corrector scheme are employed to detect numerically the chaos in the proposed fractional order financial system.
An Analysis of Higher-Order Thinking on Algebra I End-of-Course Tests
Thompson, Tony
2011-01-01
This research provides insight into one US state's effort to incorporate higher-order thinking on its Algebra I End-of-Course tests. To facilitate the inclusion of higher-order thinking, the state used "Dimensions of Thinking" (Marzano et al., 1988) and "Bloom's Taxonomy" (Bloom et al., 1956). An analysis of Algebra I test…
An Analysis of Higher-Order Thinking on Algebra I End-of-Course Tests
Thompson, Tony
2011-01-01
This research provides insight into one US state's effort to incorporate higher-order thinking on its Algebra I End-of-Course tests. To facilitate the inclusion of higher-order thinking, the state used "Dimensions of Thinking" (Marzano et al., 1988) and "Bloom's Taxonomy" (Bloom et al., 1956). An analysis of Algebra I test…
Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology
Button, Amy; Sweterlisch, Jeffery J.
2013-01-01
An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle. In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight program computer model predictions with specific operating conditions.
Treatability Test Plan for an In Situ Biostimulation Reducing Barrier
Truex, Michael J.; Vermeul, Vince R.; Long, Philip E.; Brockman, Fred J.; Oostrom, Mart; Hubbard, Susan; Borden, Robert C.; Fruchter, Jonathan S.
2007-10-26
This treatability test plan supports a new, integrated strategy to accelerate cleanup of chromium in the 100 Areas at the Hanford Site. This plan includes performing a field-scale treatability test for bioreduction of chromate, nitrate, and dissolved oxygen. In addition to remediating a portion of the plume and demonstrating reduction of electron acceptors in the plume, the data from this test will be valuable for designing a full-scale bioremediation system to apply at this and other chromium plumes at the Hanford Site.
Cryomdoule Test Stand Reduced-Magnetic Support Design at Fermilab
McGee, Mike [Fermilab; Chandrasekaran, Saravan Kumar [Fermilab; Crawford, Anthony [Fermilab; Harms, Elvin [Fermilab; Leibfritz, Jerry [Fermilab; Wu, Genfa [Fermilab
2016-06-01
In a partnership with SLAC National Accelerator Laboratory (SLAC) and Jefferson Lab, Fermilab will assemble and test 17 of the 35 total 1.3 GHz cryomodules for the Linac Coherent Light Source II (LCLS-II) Project. These devices will be tested at Fermilab's Cryomodule Test Facility (CMTF) within the Cryomodule Test Stand (CMTS-1) cave. The problem of magnetic pollution became one of major issues during design stage of the LCLS-II cryomodule as the average quality factor of the accelerating cavities is specified to be 2.7 x 10¹⁰. One of the possible ways to mitigate the effect of stray magnetic fields and to keep it below the goal of 5 mGauss involves the application of low permeable materials. Initial permeability and magnetic measurement studies regarding the use of 316L stainless steel material indicated that cold work (machining) and heat affected zones from welding would be acceptable.
Stroebel Robert J
2011-09-01
Full Text Available Abstract Background To evaluate the value of a pre-ordering process for the pro-active scheduling and completion of appropriate preventive and chronic disease monitoring tests prior to a periodic health examination (PHE. Methods A standardized template was developed and used by our nursing staff to identify and schedule appropriate tests prior to the patients PHE. Chart reviews were completed on all 602 PHE visits for a 3-month interval in a primary care setting. A patient satisfaction survey was administered to a convenience sample of the PHE patients. Results Of all the patients with tests pre-ordered, 87.8% completed the tests. All providers in the division used the process, but some evolved from one template to another over time. Most patients (61% preferred to get their tests done prior to their PHE appointment. Many of our patients had abnormal test results. With this process, patients were able to benefit from face-to-face discussion of these results directly with their provider. Conclusions A pre-order process was successfully implemented to improve the value of the PHE visit in an internal medicine primary care practice using a standardized approach that allowed for provider autonomy. The process was accepted by patients and providers and resulted in improved office efficiency through reduced message handling. Completion of routine tests before the PHE office visit can help facilitate face-to-face discussions about abnormal results and subsequent management that otherwise may only occur by telephone.
Klistorner, A; Graham, S L
2005-11-01
The multi-focal visual evoked potential (mfVEP) has been recently introduced as an alternative to subjective perimetry in detecting visual field defects. This study examines the source of variability in the mfVEP amplitude, and determines the relationship of this variability to the strength of the signal itself across the visual field. It also investigates possible means to reduce the effects of this variability on between-test interpretation to allow for easier detection of progression. 85 normal subjects participated in the study. The mfVEP was recorded using Accumap (ObjectiVision Pty Ltd, Sydney, Australia). Each subject was tested twice with an interval between visits of 3-4 weeks. Comparison between tests was performed using coefficient of variability (CV). Variability was also analysed using scaling and clustering procedures. In the majority of the retinal areas CV fell within 15-20%. Variability increased with eccentricity, but there was no age dependency. There was a significant reduction of variability (by 15.8 +/- 6%, Student's t-test p<0.0001) when a scaling procedure was applied and this was consistent at all eccentricities. A clustering procedure reduced variability on average by a further 18.5 +/- 4.5% (Student's t-test p<0.0001). This result was also consistent at all eccentricities. Between test comparisons of raw mfVEP traces is limited by a variability of at least 15%. While this variability required the amplitude of the individual VEP signal to change by 30-40% in order to detect progression, scaling and clustering procedures were able to reduce the required change to 20-25%, thus making an interpretation of consecutive test results more clinically viable.
Does parental physical violence reduce children's standardized test score performance?
Peek-Asa, Corinne; Maxwell, Leah; Stromquist, Ann; Whitten, Paul; Limbos, Mary Ann; Merchant, James
2007-11-01
Many negative cognitive and behavioral outcomes have been identified among children living in households with parental violence, but few studies have examined academic performance. In a rural population-based cohort, we examine the role of parental violence on standardized test score performance. The cohort included 306 children ages 6 through 17. Parents responded to a health interview that included questions about physical violence. Children's standardized test scores were collected prospectively for 5 years after the parent interview. Hierarchical multivariate models clustering on school, household, and repeated individual test scores and controlling for children's and parent's characteristics were run to predict test score performance. One in five children lived in a household in which parents reported at least one act of physical violence. Children whose parents reported intimate partner violence (IPV) performed an average of 12.2 percentile points lower than children whose parents reported no IPV (95% CI, -19.2--5.2; p Parent-reported IPV led to larger test score reductions for girls than for boys and for children less than 12 years old than for older children. Parental physical violence was common, and children in homes with violence had significantly poorer performance on standardized test scores.
Reduced Order Model Basis Vector Generation: Generates Basis Vectors fro ROMs
2016-03-03
libROM is a library that implements order reduction via singular value decomposition (SVD) of sampled state vectors. It implements 2 parallel, incremental SVD algorithms and one serial, non-incremental algorithm. It also provides a mechanism for adaptive sampling of basis vectors.
76 FR 13532 - Reducing Regulatory Burden; Retrospective Review Under Executive Order 13563
2011-03-14
... Executive Order 13563. SBA is also interested in comments about factors that we should consider in setting... regulations; (9) revise regulations to address changes in technology, economic conditions, or other factors... individual, personal or corporate benefit. Where feasible, comments should reference a specific...
Reduced order of the local error of splitting for parabolic problems
Auzinger, Winfried; Hofstätter, Harald; Koch, Othmar; Thalhammer, Mechthild
2017-07-01
We give a theoretical analysis of the local error of splitting methods applied to parabolic initial-boundary value problems under homogeneous Dirichlet or Neumann boundary conditions. For the Lie-Trotter splitting, we provide a theoretical local error analysis that rigorously explains the order reduction observed in numerical experiments.
Testing the Suitability of Mediation of Child Support Orders in Title IV-D Cases
Schraufnagel, Scot; Li, Quan
2010-01-01
Objectives: The purpose of this study is to test mediation versus a traditional court process for the establishment or modification of child support orders. The intention is to determine which dispute resolution process is associated with greater client satisfaction and compliance. An auxiliary objective is to test the type of cases which are most…
78 FR 59165 - Orders: Information Reporting With Respect to Stress Testing of Regulated Entities
2013-09-26
... AGENCY 12 CFR Part 1238 Orders: Information Reporting With Respect to Stress Testing of Regulated... entity) that has total consolidated assets of more than $10 billion to conduct annual stress tests to..., efficient, competitive, and resilient national housing finance markets, and that they carry out their public...
Caries risk assessment in school children using a reduced Cariogram model without saliva tests
Petersson, Gunnel Hänsel; Isberg, Per-Erik; Twetman, Svante
2010-01-01
To investigate the caries predictive ability of a reduced Cariogram model without salivary tests in schoolchildren.......To investigate the caries predictive ability of a reduced Cariogram model without salivary tests in schoolchildren....
MOLNAR A.
2009-12-01
Full Text Available In general the main objective of phytosanitary treatment is to be at high qualitative level, in high securityconditions and with low environmental impact. From this point of view there are some conditions, which must beaccomplished by the employees and by the agricultural sprayer machineries. This paper studies the order of actionsneeded for phytosanitary treatment of agricultural crops in order to reduce the environment pollution, to assure the foodsecurity and employees’ security.
2014-04-01
detailed results within certain parametric ranges at a fraction of the cost of the full governing equations. Moreover, the ROM has the further potential...but found to be inferior to upwind differencing . Similar responses at the forcing frequency are found but unlike in the case using 2nd-order...up. It is believed that this difficulty is not a characteristic of central differencing , but rather arises from using inconsistent differencing
Motivating factors for physician ordering of Factor V Leiden genetic tests
Hindorff, Lucia A.; Burke, Wylie; Laberge, Anne-Marie; Rice, Kenneth M.; Lumley, Thomas; Leppig, Kathleen; Rosendaal, Frits R.; Larson, Eric B.; Psaty, Bruce M.
2009-01-01
Background The Factor V Leiden (FVL) genetic test is used by many physicians despite its uncertain clinical utility. This study investigated whether self-reported motivations and behaviors concerning FVL genetic testing differed between two groups of primary care physicians defined by frequency of prior FVL test use. Methods In January 2007, 112 primary care physicians (60 frequent, 52 infrequent FVL test users) at Group Health, a large health care delivery system, were surveyed. Survey content areas included: primary reasons and motivating factors for ordering FVL; likelihood of ordering FVL for hypothetical patients; potential barriers to genetic testing, and practices and skills regarding FVL test ordering. Results Responses between groups agreed concerning most clinical- or patient-related factors. Frequent-FVL physicians were more likely than infrequent-FVL physicians to report ordering FVL for hypothetical patients with mesenteric venous thrombosis (adjusted OR 4.57, 95% CI 1.55, 13.53) or venous thrombosis following hospital discharge (adjusted OR 3.42, 95% CI 1.30, 8.95). Frequent-FVL physicians were also less likely to agree with several potential barriers to genetic testing and more likely to report high confidence in interpreting and explaining FVL test results. Conclusions Generally, both groups of physicians reported similar motivating factors for ordering FVL, and reported behaviors were consistent with existing guidelines. More striking differences were observed for measures such as barriers to and confidence in using genetic tests. Though additional research is necessary to evaluate their impact, these results inform several knowledge-to-practice translation issues that are important to the successful integration of genetic testing into primary care. PMID:19139326
Fang, F.; Zhang, T.; Pavlidis, D.; Pain, C. C.; Buchan, A. G.; Navon, I. M.
2014-10-01
A novel reduced order model (ROM) based on proper orthogonal decomposition (POD) has been developed for a finite-element (FE) adaptive mesh air pollution model. A quadratic expansion of the non-linear terms is employed to ensure the method remained efficient. This is the first time such an approach has been applied to air pollution LES turbulent simulation through three dimensional landscapes. The novelty of this work also includes POD's application within a FE-LES turbulence model that uses adaptive resolution. The accuracy of the reduced order model is assessed and validated for a range of 2D and 3D urban street canyon flow problems. By comparing the POD solutions against the fine detail solutions obtained from the full FE model it is shown that the accuracy is maintained, where fine details of the air flows are captured, whilst the computational requirements are reduced. In the examples presented below the size of the reduced order models is reduced by factors up to 2400 in comparison to the full FE model while the CPU time is reduced by up to 98% of that required by the full model.
Lattice Boltzmann flow simulations with applications of reduced order modeling techniques
Brown, Donald
2014-01-01
With the recent interest in shale gas, an understanding of the flow mechanisms at the pore scale and beyond is necessary, which has attracted a lot of interest from both industry and academia. One of the suggested algorithms to help understand flow in such reservoirs is the Lattice Boltzmann Method (LBM). The primary advantage of LBM is its ability to approximate complicated geometries with simple algorithmic modificatoins. In this work, we use LBM to simulate the flow in a porous medium. More specifically, we use LBM to simulate a Brinkman type flow. The Brinkman law allows us to integrate fast free-flow and slow-flow porous regions. However, due to the many scales involved and complex heterogeneities of the rock microstructure, the simulation times can be long, even with the speed advantage of using an explicit time stepping method. The problem is two-fold, the computational grid must be able to resolve all scales and the calculation requires a steady state solution implying a large number of timesteps. To help reduce the computational complexity and total simulation times, we use model reduction techniques to reduce the dimension of the system. In this approach, we are able to describe the dynamics of the flow by using a lower dimensional subspace. In this work, we utilize the Proper Orthogonal Decomposition (POD) technique, to compute the dominant modes of the flow and project the solution onto them (a lower dimensional subspace) to arrive at an approximation of the full system at a lowered computational cost. We present a few proof-of-concept examples of the flow field and the corresponding reduced model flow field.
Full-scale simulation and reduced-order modeling of a thermoacoustic engine
Scalo, Carlo; Lin, Jeff; Lele, Sanjiva; Hesselink, Lambertus
2013-11-01
We have carried out the first three-dimensional numerical simulation of a thermoacoustic Stirling heat-engine. The goal is to lay the groundwork for full-scale Navier-Stokes simulations to advance the state-of-the-art low-order modeling and design of such devices. The model adopted is a long resonator with a heat-exchanger/regenerator (HX/REG) unit on one end - the only component not directly resolved. A temperature difference across the HX/REG unit of 200 K is sufficient to initiate the thermoacoustic instability. The latter is a Lagrangian process that only intensifies acoustic waves traveling in the direction of the imposed temperature gradient. An acoustic network of traveling waves is thus obtained and compared against low-order prediction tools such as DeltaEC. Non-linear effects such as system-wide streaming flow patterns are rapidly established. These are responsible for the mean advection of hot fluid away from the HX/REG (i.e. thermal leakage). This unwanted effect is contained by the introduction of a second ambient heat-exchanger allowing for the establishment of a dynamical thermal equilibrium in the system. A limit cycle is obtained at +178 dB.
Improving Order and Mobility in MEH-PPV Films by Reducing Polydispersity
White, Jonathon
2012-02-01
The effect of polydispersity on morphology and charge transport in drop cast films of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) was investigated using grazing incidence X-ray diffraction and time-of-flight respectively. Morphologically, reducing polydispersity by removing short chain segments promoted the capability of crystallization. This resulted in higher hole mobility and non-dispersive transport down to lower temperatures for the lower polydispersity sample. The slope for the Poole-Frenkel relationship at 298 K was increased, and its change with temperature decreased, indicating reduced spatial inhomogeneity. Analysis using Bassler's Gaussian disorder model (GDM), found that the value for energy disorder (σ˜53meV for both films) and infinite temperature zero field mobility (μo˜3 x10-6 cm^2/Vs) were similar for both films. However, a good fit for hopping site separation and spatial disorder was only possible for the lower polydispersity device, suggesting that the lower polydispersity films have less mesoscopic inhomogeneity.
Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-08-31
Given that next-generation infrastructures will contain large numbers of grid-connected inverters and these interfaces will be satisfying a growing fraction of system load, it is imperative to analyze the impacts of power electronics on such systems. However, since each inverter model has a relatively large number of dynamic states, it would be impractical to execute complex system models where the full dynamics of each inverter are retained. To address this challenge, we derive a reduced-order structure-preserving model for parallel-connected grid-tied three-phase inverters. Here, each inverter in the system is assumed to have a full-bridge topology, LCL filter at the point of common coupling, and the control architecture for each inverter includes a current controller, a power controller, and a phase-locked loop for grid synchronization. We outline a structure-preserving reduced-order inverter model for the setting where the parallel inverters are each designed such that the filter components and controller gains scale linearly with the power rating. By structure preserving, we mean that the reduced-order three-phase inverter model is also composed of an LCL filter, a power controller, current controller, and PLL. That is, we show that the system of parallel inverters can be modeled exactly as one aggregated inverter unit and this equivalent model has the same number of dynamical states as an individual inverter in the paralleled system. Numerical simulations validate the reduced-order models.
Tests to Reduce TorreCat™ Technology to Practice
Westover, Tyler [Idaho National Lab. (INL), Idaho Falls, ID (United States); Emerson, Rachel Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-02-26
Torrefaction is the thermal treatment of materials in the absence of oxygen in the temperature range of 200 to 300 °C and has been shown to improve handling and grinding properties, hydrophobicity, volatiles content, energy density, and combustion performance of renewable energy biomass feedstock materials. The disadvantages of torrefaction are its relative high cost compared to the low value input feedstock material and the energy that can be lost to volatized gases. This work will demonstrate a new technology developed by Advanced Torrefaction Systems (ATS), known as TorreCat™ Technology, that uses an oxidation catalyst in a closed system to combust and destroy volatile organic compounds (VOCs) and other byproducts produced in the torrefaction process. An oxidation catalyst is a substance, or a combination of substances, that accelerate the rate of a chemical reaction without being consumed by the reaction. Catalytic combustion is a reaction that occurs at temperatures 50% lower than traditional combustion, such that essentially no NOx is created. The output of the oxidation catalyst (flue gas) consists mainly of superheated steam and inert gases (carbon dioxide and nitrogen), which can be used for heat in the thermal treatment process. INL has previously developed a pilot-scale Continuous-Feed Thermal Treatment System (CFTTS) that has 10 kg/hr capacity but does not reform the flue gas to reduce environmental concerns or capture all available heat from the biomass material. Using the TorreCat™ technology in INL’s thermal treatment system will demonstrate increased thermal efficiencies during the treatment process as well as reduced environmental impact and clean-up costs. The objective of this project is to determine the effectiveness of the Torrecat™ technology to reform the flue gas and capture as much of its heat content as possible.
Parametric Reduced-Order Models for Probabilistic Analysis of Unsteady Aerodynamic Applications
2007-01-01
method is to discretize the domain under consideration, Ω, into elements Ωe. Next, a space of polynomials of degree at most p, Uph (Ωe), is defined on...approximate solution wh can be found by enforcing the nonlinear conservation law (1) locally, for all test functions vh ∈ Uph (Ωe): ∫ Ωe vTh ∂wh ∂t dΩe...computed using the inner state and boundary condition data. The final form of the DG discretization is constructed by selecting a basis for Uph (Ωe
Gang Chen
2012-01-01
Full Text Available It is not easy for the system identification-based reduced-order model (ROM and even eigenmode based reduced-order model to predict the limit cycle oscillation generated by the nonlinear unsteady aerodynamics. Most of these traditional ROMs are sensitive to the flow parameter variation. In order to deal with this problem, a support vector machine- (SVM- based ROM was investigated and the general construction framework was proposed. The two-DOF aeroelastic system for the NACA 64A010 airfoil in transonic flow was then demonstrated for the new SVM-based ROM. The simulation results show that the new ROM can capture the LCO behavior of the nonlinear aeroelastic system with good accuracy and high efficiency. The robustness and computational efficiency of the SVM-based ROM would provide a promising tool for real-time flight simulation including nonlinear aeroelastic effects.
Reducing uncertainty in geostatistical description with well testing pressure data
Reynolds, A.C.; He, Nanqun [Univ. of Tulsa, OK (United States); Oliver, D.S. [Chevron Petroleum Technology Company, La Habra, CA (United States)
1997-08-01
Geostatistics has proven to be an effective tool for generating realizations of reservoir properties conditioned to static data, e.g., core and log data and geologic knowledge. Due to the lack of closely spaced data in the lateral directions, there will be significant variability in reservoir descriptions generated by geostatistical simulation, i.e., significant uncertainty in the reservoir descriptions. In past work, we have presented procedures based on inverse problem theory for generating reservoir descriptions (rock property fields) conditioned to pressure data and geostatistical information represented as prior means for log-permeability and porosity and variograms. Although we have shown that the incorporation of pressure data reduces the uncertainty below the level contained in the geostatistical model based only on static information (the prior model), our previous results assumed did not explicitly account for uncertainties in the prior means and the parameters defining the variogram model. In this work, we investigate how pressure data can help detect errors in the prior means. If errors in the prior means are large and are not taken into account, realizations conditioned to pressure data represent incorrect samples of the a posteriori probability density function for the rock property fields, whereas, if the uncertainty in the prior mean is incorporated properly into the model, one obtains realistic realizations of the rock property fields.
Reduced Order Models of a Current Source Inverter Induction Motor Drive
Ibrahim K. Al-Abbas
2009-01-01
Full Text Available Problem Statement: The current source inverter induction motor (CSI-IM drive was widely used in various industries. The main disadvantage of this drive was nonlinearity and complexity. This work was done to develop a simple drive systems models. Approach: The MATLAB/SIMULINK software was used for system modeling. Three reduced models were developed by choosing specific frame, neglecting stator transients and ignoring stator equations. Results: The dynamic performance of the models was examined in open loop form for a step change in control variable (the input voltage as well as for step change in disturbance (mechanical load.Conclusion: The three models were equivalent in steady state. The error of these models in the transient response was less than 5 %, with the exception of the time performances of the transient model to step change of supply voltage. Recommendations: All three models were suggested to be used for designing torque control systems. The detailed and stator equation models were recommended to be used in speed control design.
A new method of testing for Hardy–Weinberg equilibrium and ordering populations
Nader Ebrahimi; Devrim Bilgili
2007-01-01
The assumption of Hardy–Weinberg equilibrium (HWE) among alleles in a nonevolving population is of fundamental importance in genetic studies. Deviation from HWE in a population usually indicates inbreeding, stratification and sometimes problems in genotyping. In populations of affected individuals, these deviations can also provide evidence for association. In this paper, we introduce a measure based on the Kullback–Leibler discrimination information function that quantifies the deviation from HWE in a population. We use this measure to order populations. We also propose a test for HWE based on an estimate of this measure. The test is a statistically consistent test of the null hypothesis for all alternatives and is very easy to implement. Our proposed test statistic is compared with an earlier, widely used, test. Finally, the use of the proposed new test is shown in an illustrative example.
Mediaas, Heidi; Grande, Knut; Hustad, Britt-Marie; Hoevik, Kim Reidar; Kummernes, Hege; Nergaard, Bjoern; Vindstad, Jens Emil
2006-03-15
Producing and refining high-TAN crude oils introduces a number of challenges, among which calcium naphthenate deposition in process facilities is the most serious production issue. Until recently, the only option for studying chemicals and process parameters in order to prevent naphthenate deposition has been field tests. Statoil has now developed a small scale pilot plant where these experiments can be performed in the laboratory at Statoil's Research and Technology Center in Trondheim, Norway. The results from the pilot plant are in full agreement with the extensive naphthenate experience obtained from almost 9 years operation of the Heidrun oilfield. The design and operational procedures for this test facility are based on the recent discovery by Statoil and ConocoPhillips of the ARN acid. The ARN acid is a prerequisite for calcium naphthenate deposition. The new continuous flow pilot plant, the Naphthenate Rig, is used to develop new environmental friendly naphthenate inhibitors and to optimize process operating conditions. Since it operates on real crudes the need for field tests in qualifying new naphthenate inhibitors is reduced. To the best of our knowledge, the rig is the first of its kind in the world. (Author)
Xingling, Shao; Honglun, Wang
2015-07-01
This paper proposes a novel composite integrated guidance and control (IGC) law for missile intercepting against unknown maneuvering target with multiple uncertainties and control constraint. First, by using back-stepping technique, the proposed IGC law design is separated into guidance loop and control loop. The unknown target maneuvers and variations of aerodynamics parameters in guidance and control loop are viewed as uncertainties, which are estimated and compensated by designed model-assisted reduced-order extended state observer (ESO). Second, based on the principle of active disturbance rejection control (ADRC), enhanced feedback linearization (FL) based control law is implemented for the IGC model using the estimates generated by reduced-order ESO. In addition, performance analysis and comparisons between ESO and reduced-order ESO are examined. Nonlinear tracking differentiator is employed to construct the derivative of virtual control command in the control loop. Third, the closed-loop stability for the considered system is established. Finally, the effectiveness of the proposed IGC law in enhanced interception performance such as smooth interception course, improved robustness against multiple uncertainties as well as reduced control consumption during initial phase are demonstrated through simulations.
А. Г. Стрельников
2016-01-01
Full Text Available Objective. Prior animal studies suggest that botulinum toxin injection into the epicardial fat pads can suppress atrial fibrillation (AF inducibility. The purpose of the present study was to assess the efficacy and safety of endocardial botulinum toxin injection into epicardial fat pads and intramyocardial left atrial ganglionated plexi (GP for preventing AF.Methods. Twenty-four dogs were separated into 3 groups: endocardial approach for botulinum toxin (Xeomin, Germany injection into epicardial fat pads and intramyocardial GPs; endocardial approach for placebo injection (0.9% normal saline; control 1; n = 8 and epicardial approach for botulinum toxin injection (control 2; n = 8.Results. A mean of 6.9±1.7 intramyocardial injections (10 U/0.2 mL at each and 3 injections (50 U/1 mL at each were administered into each site exhibiting a positive vagal response and into each epicardial fat pad in all groups (p>0.05 between groups.The injections of botulinum toxin demonstrated dramatic prolongation of ERP in all PV-atrial junctions. This effect correlated with less pronounced ERP shortening in response to vagal nerve stimulation. Suppression of AF inducibility was observed at 7 days after endocardial botulinum toxin injections. The level of AF inducibility was: at 7 days – 57% (p<0.001 vs placebo; p<0.001 vs baseline; at 14 days – 61% (p<0.001 vs placebo; p<0.001 vs baseline; at 1 month – 38% (p<0.001 vs placebo; p<0.001 vs baseline; at 3 months – 23% (p = 0.003; p = 0.06 vs baseline. There were no differences between botulinum groups (p>0.05 for all. The effect of AF suppression disappeared at 3 months. No procedure-related complications occurred.Conclusion. Botulinum toxin injection into intramyocardial GPs and epicardial fat pads by an endocardial approach is feasible and safe. It provides complete removal of cardiac vagal responses and reliably reduces vulnerability to atrial fibrillation.
A Test Procedure for Ordered Hypothesis of Population Proportions Against a Control
Waheed Babatunde YAHYA
2016-04-01
Full Text Available Objective: This paper aims to present a novel procedure for testing a set of population proportions against an ordered alternative with a control. Material and Methods: The distribution of the test statistic for the proposed test was determined theoretically and through Monte-Carlo experiments. The efficiency of the proposed test method was compared with the classical Chi-square test of homogeneity of population proportions using their empirical Type I error rates and powers at various sample sizes. Results: The new test statistic that was developed for testing a set of population proportions against an ordered alternative with a control was found to have a Chi-square distribution with non-integer values degrees of freedom v that depend on the number of population groups k being compared. Table of values of v for comparing up to 26 population groups was constructed while an expression was developed to determine v for cases where k > 26. Further results showed that the new test method is capable of detecting the superiority of a treatment, for instance a new drug type, over some of the existing ones in situations where only the qualitative data on users’ preferences of all the available treatments (drug types are available. The new test method was found to be relatively more powerful and consistent at estimating the nominal Type I error rates (α, especially at smaller sample sizes than the classical Chi-square test of homogeneity of population proportions. Conclusion: Conclusion: Conclusion: Conclusion: The new test method proposed here could find applications in pharmacology where a newly developed drug might be expected to be more preferred by users than some of the existing ones. This kind of test problem can equally exist in medicine, engineering and humanities in situations where only the qualitative data on users’ preferences of a set of treatments or systems are available.
Trehan, Sumeet; Durlofsky, Louis J.
2016-12-01
A new reduced-order model based on trajectory piecewise quadratic (TPWQ) approximations and proper orthogonal decomposition (POD) is introduced and applied for subsurface oil-water flow simulation. The method extends existing techniques based on trajectory piecewise linear (TPWL) approximations by incorporating second-derivative terms into the reduced-order treatment. Both the linear and quadratic reduced-order methods, referred to as POD-TPWL and POD-TPWQ, entail the representation of new solutions as expansions around previously simulated high-fidelity (full-order) training solutions, along with POD-based projection into a low-dimensional space. POD-TPWQ entails significantly more offline preprocessing than POD-TPWL as it requires generating and projecting several third-order (Hessian-type) terms. The POD-TPWQ method is implemented for two-dimensional systems. Extensive numerical results demonstrate that it provides consistently better accuracy than POD-TPWL, with speedups of about two orders of magnitude relative to high-fidelity simulations for the problems considered. We demonstrate that POD-TPWQ can be used as an error estimator for POD-TPWL, which motivates the development of a trust-region-based optimization framework. This procedure uses POD-TPWL for fast function evaluations and a POD-TPWQ error estimator to determine when retraining, which entails a high-fidelity simulation, is required. Optimization results for an oil-water problem demonstrate the substantial speedups that can be achieved relative to optimizations based on high-fidelity simulation.
2012-03-14
..., Endocrine disruptors, Pesticides and pests. Dated: February 17, 2012. Lois Rossi, Director, Registration... AGENCY Results From Inert Ingredient Test Orders Issued Under EPA's Endocrine Disruptor Screening Program... EPA's Endocrine Disruptor Screening Program (EDSP) and the Federal Food, Drug, and Cosmetic Act...
Using Tests To Evaluate the Impact of Curricular Reform on Higher Order Thinking.
Davis, Alan
The dominant issues in considering the use of tests developed outside the classroom to measure the impact of curriculum reform on higher order thinking are reviewed by a panel interviewed for this discussion. Panel members are: (1) Stuart Kahl, (2) Robert Linn, (3) Senta A. Raizen, (4) Lauren Resnick, and (5) Thomas A. Romberg. It is conceded…
Christensen, Bent Jesper; Kruse, Robinson; Sibbertsen, Philipp
We consider hypothesis testing in a general linear time series regression framework when the possibly fractional order of integration of the error term is unknown. We show that the approach suggested by Vogelsang (1998a) for the case of integer integration does not apply to the case of fractional...
A reduced-order model of three-dimensional unsteady flow in a cavity based on the resolvent operator
Gómez, F; Rudman, M; Sharma, AS; McKeon, BJ
2016-01-01
A novel reduced-order model for nonlinear flows is presented. The model arises from a resolvent decomposition in which the nonlinear advection terms of the Navier-Stokes equation are considered as the input to a linear system in Fourier space. Results show that Taylor-G\\"ortler-like vortices can be represented from a low-order resolvent decomposition of a nonlinear lid-driven cavity flow. The present approach provides an approximation of the fluctuating velocity given the time-mean and the time history of a single velocity probe.
Reducing variety in product solution spaces of engineer-to-order companies: The case of Novenco A/S
Haug, Anders; Hvam, Lars; Mortensen, Niels Henrik
2013-01-01
. To support ETO companies in achieving more efficient product solution spaces, this paper presents a procedure for reducing product solution spaces in ETO companies. The procedure is demonstrated through an action research study at the Danish ETO company, Novenco, which develops and manufactures heating...... by eliminating the product variety that do not create customer value. However, for Engineer-to-Order (ETO) companies, elimination of variety is particularly challenging, since it is about reducing variety in a complex product solution space, rather than just eliminating already produced product variants...
Variable aberration generator using a high-order even aspheric singlet for testing optical surfaces
Lu, Jinfeng; Chen, Shanyong; Xue, Shuai
2016-10-01
Traditional null optics is generally designed for a particular optical surface. It must be redesigned when the test surface is changed no matter the null optic is reflective, transmitted or a CGH. Development of advanced optical machining and testing based on deterministic figuring and null test makes it possible to apply high-order aspheres. This paper presents a plano-concave singlet to realize variable aberration correction for testing different surfaces. The concave surface is an even asphere with high-order terms. By changing the axial distances among the transmission sphere, the null singlet and the test surface, variable aberrations are generated to meet the aberration balance requirement for various surfaces. The residual aberrations are confirmed within the vertical dynamic range of measurement of the interferometer. It enables flexible testing of optical surfaces without dedicated null optics. The optical design verifies that the aspheric singlet can be used to test conic surfaces with different conic constant and radius of curvature ranging from ellipsoid, paraboloid to hyperboloid and an even asphere.
Ma, Chao; Xu, Dan; King, Kevin F; Liang, Zhi-Pei
2013-02-01
The performance of multidimensional spatially selective radiofrequency (RF) pulses is often limited by their long duration. In this article, high-order, nonlinear gradients are exploited to reduce multidimensional RF pulse length. Specifically, by leveraging the multidimensional spatial dependence of second-order gradients, a two-dimensional spatial-spectral RF pulse is designed to achieve three-dimensional spatial selectivity, i.e., to excite a circular region-of-interest in a thin slice for reduced field-of-view imaging. Compared to conventional methods that use three-dimensional RF pulses and linear gradients, the proposed method requires only two-dimensional RF pulses, and thus can significantly shorten the RF pulses and/or improve excitation accuracy. The proposed method has been validated through Bloch equation simulations and phantom experiments on a commercial 3.0T MRI scanner.
Pereira, Heverton A.; F. Cupertino, Allan; Teodorescu, Remus
2014-01-01
Wind power has achieved technological evolution, and Grid Code (GC) requirements forced wind industry consolidation in the last three decades. However, more studies are necessary to understand how the dynamics inherent in this energy source interact with the power system. Traditional energy...... in interconnection studies of synchronous machines with full converter technology. The performance of all models is evaluated based on time domain simulations in the Simulink/MATLAB environment. A detailed model is described, and four reduced order models are compared using the performance index, Normalized Integral...... of Absolute Error (NIAE). Models are analyzed during wind speed variations and balanced voltage dip. During faults, WPPs must be able to supply reactive power to the grid, and this characteristic is analyzed. Using the proposed performance index, it is possible to conclude if a reduced order model is suitable...
Xia, Hong; Luo, Zhendong
2017-01-01
In this study, we devote ourselves to establishing a stabilized mixed finite element (MFE) reduced-order extrapolation (SMFEROE) model holding seldom unknowns for the two-dimensional (2D) unsteady conduction-convection problem via the proper orthogonal decomposition (POD) technique, analyzing the existence and uniqueness and the stability as well as the convergence of the SMFEROE solutions and validating the correctness and dependability of the SMFEROE model by means of numerical simulations.
Hernandez S, A. [UNAM, Laboratorio de Analisis de Ingenieria de Reactores Nucleares, DEPFI, Campus Morelos, en IMTA Jiutepec, Morelos (Mexico)]. e-mail: augusto@correo.unam.mx
2004-07-01
The present work has as objective to analyze the relative stability of a BWR type reactor. It is analyzed that so adaptive it turns out to identify the parameters of a model of reduced order so that this it reproduces a condition of given uncertainty. This will take of a real fact happened in the La Salle plant under certain operation conditions of power and flow of coolant. The parametric identification is carried out by means of an algorithm of recursive least square and an Output Error model (Output Error), measuring the output power of the reactor when the instability is present, and considering that it is produced by a change in the reactivity of the system in the same way that a sign of type step. Also it is carried out an analytic comparison of the relative stability, analyzing two types of answers: the original answer of the uncertainty of the reactor vs. the obtained response identifying the parameters of the model of reduced order, reaching the conclusion that it is very viable to adapt a model of reduced order to study the stability of a reactor, under the only condition to consider that the dynamics of the reactivity is of step type. (Author)
Heverton A. Pereira
2014-11-01
Full Text Available Wind power has achieved technological evolution, and Grid Code (GC requirements forced wind industry consolidation in the last three decades. However, more studies are necessary to understand how the dynamics inherent in this energy source interact with the power system. Traditional energy production usually contains few high power unit generators; however, Wind Power Plants (WPPs consist of dozens or hundreds of low-power units. Time domain simulations of WPPs may take too much time if detailed models are considered in such studies. This work discusses reduced order models used in interconnection studies of synchronous machines with full converter technology. The performance of all models is evaluated based on time domain simulations in the Simulink/MATLAB environment. A detailed model is described, and four reduced order models are compared using the performance index, Normalized Integral of Absolute Error (NIAE. Models are analyzed during wind speed variations and balanced voltage dip. During faults, WPPs must be able to supply reactive power to the grid, and this characteristic is analyzed. Using the proposed performance index, it is possible to conclude if a reduced order model is suitable to represent the WPPs dynamics on grid studies.
M Ghari
2015-09-01
Full Text Available Introduction: Nowadays the number of motor vehicles in large and small cities is growing. Increasing the number of motor vehicles leads to serious increase of the amount of environmental pollution and daily fuel consumption. Motor vehicle emissions that are known as the most air polluting emissions cause 50-90 percent of air pollution. With large increasd in the number of motor vehicles and their emissions todays, many researchers have investigated engine optimization in order to reduce emissions of motor vehicles. But due to the lack of affordable changes in the physical structure of the engine, it is not possible to create major changes in the amount of engine exhaust. Hence, in order to improve engine performance and reduce emissions, a lot of research has been carried out on changes in the fuel and engine inlet air. So, in this study a new method has been proposed and tested in order to detect changes in the charactristics of emissions. So, the effects of enriched nitrous oxide gas on the exhaust emissions of a spark-injection engine were investigated. In this way, a certain amount of Nitrous Oxide (N2O gas was mixed with the engine inlet air (with concentration of 0, 4, 8, 12 and 16 percent and it was injected to the engine. Then its effect was studied on emission parameters at various engine rotational speeds. Then, by using genetic algorithm, the optimal values of N2O concentration and engine rotational speed were determined to reach the minimum emission parameters. Materials and Methods: To measure the engine emission parameters including CO, CO2, HC and NOx, the expriments were conducted after preparing a system to inject inlet air with different percentages of N2O into an Otto engine (model: M13NI. In this study, the randomized complete block design was used to investigate the effect of N2O concentration (five levels and engine rotational speed (three levels on exhauste emission parameters. Each expriment was replicated 9 times. For
Use of predefined biochemical admission profiles does not reduce the number of tests or total cost
Pareek, Manan; Haidl, Felix; Folkestad, Lars
2014-01-01
The objective of this pilot study was to evaluate whether the use of predefined biochemical profiles as an alternative to individually ordered blood tests by the treating physicians resulted in fewer tests or a lower total cost.......The objective of this pilot study was to evaluate whether the use of predefined biochemical profiles as an alternative to individually ordered blood tests by the treating physicians resulted in fewer tests or a lower total cost....
Wang, Chengwen; Quan, Long; Zhang, Shijie; Meng, Hongjun; Lan, Yuan
2017-03-01
Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with the high stiffness control and mismatched uncertainties input problems, which hinder direct applications of many advanced control approaches in the hydraulic servo fields. In this paper, by introducing the singular value perturbation theory, the original double-dynamics coupling model of the hydraulic servomechanism was reduced to a integral chain system. So that, the popular ADRC (active disturbance rejection control) technology could be directly applied to the reduced system. In addition, the high stiffness control and mismatched uncertainties input problems are avoided. The validity of the simplified model is analyzed and proven theoretically. The standard linear ADRC algorithm is then developed based on the obtained reduced-order model. Extensive comparative co-simulations and experiments are carried out to illustrate the effectiveness of the proposed method.
Functionality test for drug safety alerting in computerized physician order entry systems.
van der Sijs, Heleen; Bouamar, Rachida; van Gelder, Teun; Aarts, Jos; Berg, Marc; Vulto, Arnold
2010-04-01
To evaluate the functionality of drug safety alerting in hospital computerized physician order entry (CPOE) systems by a newly developed comprehensive test. Comparative evaluation of drug safety alerting quality in 6 different CPOEs used in Dutch hospitals, by means of 29 test items for sensitivity and 19 for specificity in offices of CPOE system vendors. Sensitivity and specificity were calculated for the complete test, and for the categories "within-order checks", "patient-specific checks", and "checks related to laboratory data and new patient conditions". Qualitative interviews with 16 hospital pharmacists evaluating missing functionality and corresponding pharmacy checks. Sensitivity ranged from 0.38 to 0.79 and specificity from 0.11 to 0.84. The systems achieved the same ranking for sensitivity as for specificity. Within-order checks and patient-specific checks were present in all systems; alert generation or suppression due to laboratory data and new patient conditions was largely absent. Hospital pharmacists unanimously rated checks on contra-indications (absent in 2 CPOEs) and dose regimens less than once a day (absent in 4 CPOEs) as important. Pharmacists' opinions were more divergent for other test items. A variety of pharmacy checks were used, and clinical rules developed, to address missing functionality. Our test revealed widely varying functionality and appeared to be highly discriminative. Basic clinical decision support was partly absent in two CPOEs. Hospital pharmacists did not rate all test items as important and tried to accommodate the lacking functionality by performing additional checks and developing clinical rules. (c) 2010 Elsevier Ireland Ltd. All rights reserved.
Naugler, Christopher T; Guo, Maggie
2016-04-01
There is a need to develop and validate new metrics to access the appropriateness of laboratory test requests. The mean abnormal result rate (MARR) is a proposed measure of ordering selectivity, the premise being that higher mean abnormal rates represent more selective test ordering. As a validation of this metric, we compared the abnormal rate of lab tests with the number of tests ordered on the same requisition. We hypothesized that requisitions with larger numbers of requested tests represent less selective test ordering and therefore would have a lower overall abnormal rate. We examined 3,864,083 tests ordered on 451,895 requisitions and found that the MARR decreased from about 25% if one test was ordered to about 7% if nine or more tests were ordered, consistent with less selectivity when more tests were ordered. We then examined the MARR for community-based testing for 1,340 family physicians and found both a wide variation in MARR as well as an inverse relationship between the total tests ordered per year per physician and the physician-specific MARR. The proposed metric represents a new utilization metric for benchmarking relative selectivity of test orders among physicians. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Renaud, Guillaume; Talmant, Maryline; Marrelec, Guillaume
2016-10-01
The nonlinear elasticity of solids at the microstrain level has been recently studied by applying dynamic acousto-elastic testing. It is the analog of conventional quasi-static acousto-elastic experiments but the strain-dependence (or stress-dependence) of ultrasonic wave-speed is measured with an applied strain ranging from 10-7 to 10-5 and produced by a stationary elastic wave. In conventional quasi-static acousto-elastic experiments, the strain is applied in a quasi-static manner; it exceeds 10-4 and can reach 10-2. In this work, we apply dynamic acousto-elastic testing to measure the third-order elastic constants of two isotropic materials: polymethyl methacrylate and dry Berea sandstone. The peak amplitude of the dynamic applied strain is 8 × 10-6. The method is shown to be particularly suitable for materials exhibiting large elastic nonlinearity like sandstones, since the measurement is performed in the domain of validity of the third-order hyperelastic model. In contrast, conventional quasi-static acousto-elastic experiments in such materials are often performed outside the domain of validity of the third-order hyperelastic model and the stress-dependence of the ultrasonic wave-speed must be extrapolated at zero stress, leading to approximate values of the third-order elastic constants. The uncertainty of the evaluation of the third-order elastic constants is assessed by repeating multiple times the measurements and with Monte-Carlo simulations. The obtained values of the Murnaghan third-order elastic constants are l = -73 GPa ± 9%, m = -34 GPa ± 9%, and n = -61 GPa ± 10% for polymethyl methacrylate, and l = -17 000 GPa ± 20%, m = -11 000 GPa ± 10%, and n = -30 000 GPa ± 20% for dry Berea sandstone.
Utilization of Emotional Freedom Techniques (EFT) to Reduce Test Anxiety in High Stakes Testing
Mohler, Marie Elaine
2013-01-01
There are many reasons a person may fail a high stakes test such as the National Council Licensure Examination for Registered Nurses (NCLEX-RN®). Sleep deprivation, illness, life stressors, knowledge deficit, and test anxiety are some of the common explanations. A student with test anxiety may feel threatened by this evaluation process. This…
Decker, Scott L; Englund, Julia A; Roberts, Alycia M
2014-01-01
Factor-analytic studies support a hierarchical four-factor model for the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) with a prominent general, third-order factor. However, there is substantial disagreement on which type of higher-order model best fits the data and how different models should guide test interpretation in clinical practice, with many studies concluding interpretation should primarily be focused on general indicators of intelligence. We performed a series of confirmatory factor analyses with the WISC-IV standardization sample (N = 2,200, ages 6-16 years) to examine model fit and reexamined models used to support test interpretation at the general level. Consistent with previous research, bifactor models were difficult to identify; however, compared with bifactor and hierarchical models, the correlated factors model with no general higher-order factor provided the best fit to the data. Results from this study support the basic four-factor model specified in the WISC-IV technical manual, with test interpretation primarily focused at the factor level, rather than the general level suggested in previous studies.
Yamamoto, Loren G
2014-10-01
A survey of Emergency Department (ED) clinicians (ie, physicians, nurses and clinical assistants) at a single hospital in Honolulu, Hawai'i was conducted to assess the frequency of errors in charting, and entering orders on the wrong patient's chart in the electronic medical record (EMR), and clinician opinion was sought on whether a simple watermark of the patient's room number might help reduce the number of these EMR "wrong patient errors." ED clinicians (68 total surveys) were asked if and how often they charted in the wrong patient's chart or entered an order (physicians only) in the wrong patient's chart. Physicians had a combined self-reported average error rate of 1.3%. Mean rate of patient charting errors occurred at 0.5 errors and 0.4 errors per 100 hours, for nurses and clinical assistants, respectively. The majority (81%) of the 68 clinicians surveyed felt that a room number watermark would eliminate most of the wrong patient errors. In conclusion, charting on the wrong patient and order entry on the wrong patient type errors occur with varying frequencies amongst ED clinicians. Nearly all the clinicians believe that a room number watermark might be an effective strategy to reduce these errors.
Feedback control of unstable steady states of flow past a flat plate using reduced-order estimators
Ahuja, Sunil
2009-01-01
We present an estimator-based control design procedure for flow control, using reduced-order models of the governing equations, linearized about a possibly unstable steady state. The reduced models are obtained using an approximate balanced truncation method that retains the most controllable and observable modes of the system. The original method is valid only for stable linear systems, and we present an extension to unstable linear systems. The dynamics on the unstable subspace are represented by projecting the original equations onto the global unstable eigenmodes, assumed to be small in number. A snapshot-based algorithm is developed, using approximate balanced truncation, for obtaining a reduced-order model of the dynamics on the stable subspace. The proposed algorithm is used to study feedback control of 2-D flow over a flat plate at a low Reynolds number and at large angles of attack, where the natural flow is vortex shedding, though there also exists an unstable steady state. For control design, we de...
Effectiveness of Structured Psychodrama and Systematic Desensitization in Reducing Test Anxiety.
Kipper, David A.; Giladi, Daniel
1978-01-01
Students with examination anxiety took part in study of effectiveness of two kinds of treatment, structured psychodrama and systematic desensitization, in reducing test anxiety. Results showed that subjects in both treatment groups significantly reduced test-anxiety scores. Structured psychodrama is as effective as systematic desensitization in…
Wang, Shuai; Wang, Yu; Zi, Yanyang; Li, Bing; He, Zhengjia
2015-10-01
A novel reduced-order modeling method is presented in this paper for dynamics analysis of rotating impeller-shaft-bearing assembly with cracked impellers. Based on three-dimensional finite element model, the complex component mode synthesis (CMS) method is employed to generate an efficient reduced-order model (ROM) for studying the effects of crack on the global vibration of the rotating assembly. First, a modeling framework for impeller-shaft-bearing systems in rotating frame is presented. Rotational effects, including Coriolis matrix and centrifugal softening, have been taken into account. Then, the governing equation of motion of the damped gyroscopic system is reduced by the complex CMS method. Finally, the obtained ROM is employed to study the effects of crack on assembly's vibration. During the steady-state response analysis, external excitations on the impeller due to rotor-stator interactions have been taken into account, which was however neglected in previous investigations on rotordynamics. Numerical results show that the lower-order eigenvalues and the unbalance response of the assembly are not sensitive to the local crack on impeller. Nevertheless, the flexible coupling between impeller and shaft becomes more complex when the air flow-induced excitations are considered. Under EO1 traveling wave excitations, a crack leads to slight changes in the assembly's response. In contrast, the effect of crack becomes significant when the assembly is excited by EO2 and higher EO excitations. Moreover, the nonlinear crack breathing effects affect the assembly's response obviously. Finally, a potential technique for detecting the crack on impeller during operation is discussed.
Kyngdon, Andrew; Richards, Ben
2007-01-01
This article is the final in the series on unidimensional unfolding. The investigations of Kyngdon (2006b) and Michell (1994) were extended to include direct probabilistic tests of the quantitative and ordinal components of unfolding theory with the multinomial Dirichlet model (Karabatsos 2005); and tests of the higher order axiomatic conjoint measurement (ACM, Krantz, Luce, Suppes and Tversky (KLST) 1971) condition of triple cancellation. Strong Dirichlet model support for both the ordinal and quantitative components of unfolding was only found in datasets that satisfied at least double cancellation. In contrast, the Item Response Theory (IRT) simple hyperbolic cosine model for pairwise preferences (SHCMpp, Andrich 1995) fitted all datasets. The paper concluded the SHCMpp is suited to the instrumental rather than scientific task (Michell 2000) of psychological measurement; with the caveat of the problematic chi square fit statistic. The paper also presents original work by the second author on coherent tests of triple cancellation.
Middleborns disadvantaged? Testing birth-order effects on fitness in pre-industrial Finns.
Faurie, Charlotte; Russell, Andrew F; Lummaa, Virpi
2009-05-25
Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal) middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle- and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first- or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition.
Izraelevitz, Jacob; Triantafyllou, Michael
2016-11-01
Flapping wings in nature demonstrate a large force actuation envelope, with capabilities beyond the limits of static airfoil section coefficients. Puffins, guillemots, and other auks particularly showcase this mechanism, as they are able to both generate both enough thrust to swim and lift to fly, using the same wing, by changing the wing motion trajectory. The wing trajectory is therefore an additional design criterion to be optimized along with traditional aircraft parameters, and could possibly enable dual aerial/aquatic flight. We showcase finite aspect-ratio flapping wing experiments, dynamic similarity arguments, and reduced-order models for predicting the performance of flapping wings that carry out complex motion trajectories.
Andersen, S. J.; Sørensen, J. N.; Mikkelsen, R.
2014-12-01
The turbulence in the interior of an idealised wind farm is simulated using Large Eddy Simulation and the Actuator Line technique implemented in the Navier-Stokes equations. The simulation is carried out for an 'infinitely' long row of turbines simulated by applying cyclic boundary conditions at the inlet and outlet. The simulations investigate the turbulence inherent to the wind turbines as no ambient turbulence or shear is added to this idealised case. A Reduced Order Model for the highly turbulent flow deep inside a wind farm is proposed based on a Proper Orthogonal Decomposition. The reconstructed flow is shown to capture the large scale motions of the highly turbulent flow.
Castro-Ramírez, Joel, E-mail: ingcastro.7@gmail.com [Universidad Politécnica de Tlaxcala Av. Universidad Politecnica de Tlaxcala No.1, San Pedro Xalcaltzinco, Tepeyanco, Tlaxcala, C.P. 90180 (Mexico); Martínez-Guerra, Rafael, E-mail: rguerra@ctrl.cinvestav.mx [Departamento de Control Automático CINVESTAV-IPN, A.P. 14-740, D.F., México C.P. 07360 (Mexico); Cruz-Victoria, Juan Crescenciano, E-mail: juancrescenciano.cruz@uptlax.edu.mx [Universidad Politécnica de Tlaxcala Av. Universidad Politécnica de Tlaxcala No.1, San Pedro Xalcaltzinco, Tepeyanco, Tlaxcala, C.P. 90180 (Mexico)
2015-10-15
This paper deals with the master-slave synchronization scheme for partially known nonlinear chaotic systems, where the unknown dynamics is considered as the master system and we propose the slave system structure which estimates the unknown states. It introduced a new reduced order observer, using the concept of Algebraic Observability; we applied the results to a Sundarapandian chaotic system, and by means of some numerical simulations we show the effectiveness of the suggested approach. Finally, the proposed observer is utilized for encryption, where encryption key is the master system and decryption key is the slave system.
A New DFT Architecture to Reduce Test Data Volume and Test Application Time
Ling, Zhang; Jishun, Kuang; Junjin, Mei
2016-01-01
This paper proposes a new DFT Architecture that contains three test scan modes. The test data could be interval broadcast to scan chains whenever the data in corresponding locations are compatible. Compared with the conventional broadcast scan architecture, the proposed architecture achieves better compression ratio in all cases, and the test application time is also induced. The hardware overhead is very low. Both theoretical and experimental results prove efficacy and versatility of the pro...
COMBINING REUSABLE TEST CASES AND CONTINUOUS SECURITY TESTING FOR REDUCING WEB APPS SECURITY RISKS
Sen-Tarng Lai
2016-11-01
Full Text Available In network communication age, information technology is being at the continuous and rapid evolutionprocess. Network access equipment, information system and Web Apps must rapidly and continuouslyupdate to meet the user interested requirements. Major challenge of Web Apps frequent changes is the security of user personal data and transactions information. Vulnerability scanning and penetration testing are the routine methods to improve the security of Web App. However, these two ways not only timeconsuming,but also require too many resources. For coping the continuous changes, in the limitedresources, security testing not only need to be timely completed, but also should concern testing quality.Otherwise, every change maintenance cannot avoid to cause the security risk of new version App. Based on reusable test cases, this paper proposes the continuous security testing procedure (CSTP, using test casesreusability to increase security test efficiency. In Web Apps maintenance process of limited resources, CSTPcan timely handle security testing and quickly identify Web Apps vulnerabilities and defects. Assisting Apps maintainer effectively repair security defects and concretely improve the security of user personal data and transaction information.
Reducing the Cost of Model-Based Testing through Test Case Diversity
Hemmati, Hadi; Arcuri, Andrea; Briand, Lionel
Model-based testing (MBT) suffers from two main problems which in many real world systems make MBT impractical: scalability and automatic oracle generation. When no automated oracle is available, or when testing must be performed on actual hardware or a restricted-access network, for example, only a small set of test cases can be executed and evaluated. However, MBT techniques usually generate large sets of test cases when applied to real systems, regardless of the coverage criteria. Therefore, one needs to select a small enough subset of these test cases that have the highest possible fault revealing power. In this paper, we investigate and compare various techniques for rewarding diversity in the selected test cases as a way to increase the likelihood of fault detection. We use a similarity measure defined on the representation of the test cases and use it in several algorithms that aim at maximizing the diversity of test cases. Using an industrial system with actual faults, we found that rewarding diversity leads to higher fault detection compared to the techniques commonly reported in the literature: coverage-based and random selection. Among the investigated algorithms, diversification using Genetic Algorithms is the most cost-effective technique.
Deterministic Black-Box Identity Testing $\\pi$-Ordered Algebraic Branching Programs
Jansen, Maurice; Sarma, Jayalal
2010-01-01
In this paper we study algebraic branching programs (ABPs) with restrictions on the order and the number of reads of variables in the program. Given a permutation $\\pi$ of $n$ variables, for a $\\pi$-ordered ABP ($\\pi$-OABP), for any directed path $p$ from source to sink, a variable can appear at most once on $p$, and the order in which variables appear on $p$ must respect $\\pi$. An ABP $A$ is said to be of read $r$, if any variable appears at most $r$ times in $A$. Our main result pertains to the identity testing problem. Over any field $F$ and in the black-box model, i.e. given only query access to the polynomial, we have the following result: read $r$ $\\pi$-OABP computable polynomials can be tested in $\\DTIME[2^{O(r\\log r \\cdot \\log^2 n \\log\\log n)}]$. Our next set of results investigates the computational limitations of OABPs. It is shown that any OABP computing the determinant or permanent requires size $\\Omega(2^n/n)$ and read $\\Omega(2^n/n^2)$. We give a multilinear polynomial $p$ in $2n+1$ variables ov...
Farag, Mohammed; Fleckenstein, Matthias; Habibi, Saeid
2017-02-01
Model-order reduction and minimization of the CPU run-time while maintaining the model accuracy are critical requirements for real-time implementation of lithium-ion electrochemical battery models. In this paper, an isothermal, continuous, piecewise-linear, electrode-average model is developed by using an optimal knot placement technique. The proposed model reduces the univariate nonlinear function of the electrode's open circuit potential dependence on the state of charge to continuous piecewise regions. The parameterization experiments were chosen to provide a trade-off between extensive experimental characterization techniques and purely identifying all parameters using optimization techniques. The model is then parameterized in each continuous, piecewise-linear, region. Applying the proposed technique cuts down the CPU run-time by around 20%, compared to the reduced-order, electrode-average model. Finally, the model validation against real-time driving profiles (FTP-72, WLTP) demonstrates the ability of the model to predict the cell voltage accurately with less than 2% error.
Pürrer, Michael
2016-03-01
I provide a frequency domain reduced order model (ROM) for the aligned-spin effective-one-body model "SEOBNRv2" for data analysis with second- and third-generation ground-based gravitational wave (GW) detectors. SEOBNRv2 models the dominant mode of the GWs emitted by the coalescence of black hole binaries. The large physical parameter space (dimensionless spins -1 ≤χi≤0.99 and symmetric mass ratios 0.01 ≤η ≤0.25 ) requires sophisticated reduced order modeling techniques, including patching in the parameter space and in frequency. I find that the time window over which the inspiral-plunge and the merger-ringdown waveform in SEOBNRv2 are connected has a discontinuous dependence on the parameters when the spin parameter χ =0.8 or the symmetric mass ratio η ˜0.083 . This discontinuity increases resolution requirements for the ROM. The ROM can be used for compact binary systems with total masses of 2 M⊙ or higher for the Advanced LIGO design sensitivity and a 10 Hz lower cutoff frequency. The ROM has a worst mismatch against SEOBNRv2 of ˜1 %, but in general mismatches are better than ˜0.1 %. The ROM is crucial for key data analysis applications for compact binaries, such as GW searches and parameter estimation carried out within the LIGO Scientific Collaboration.
Akhtar, Imran; Nayfeh, Ali H.; Ribbens, Calvin J.
2009-07-01
Proper orthogonal decomposition (POD) has been used to develop a reduced-order model of the hydrodynamic forces acting on a circular cylinder. Direct numerical simulations of the incompressible Navier-Stokes equations have been performed using a parallel computational fluid dynamics (CFD) code to simulate the flow past a circular cylinder. Snapshots of the velocity and pressure fields are used to calculate the divergence-free velocity and pressure modes, respectively. We use the dominant of these velocity POD modes (a small number of eigenfunctions or modes) in a Galerkin procedure to project the Navier-Stokes equations onto a low-dimensional space, thereby reducing the distributed-parameter problem into a finite-dimensional nonlinear dynamical system in time. The solution of the reduced dynamical system is a limit cycle corresponding to vortex shedding. We investigate the stability of the limit cycle by using long-time integration and propose to use a shooting technique to home on the system limit cycle. We obtain the pressure-Poisson equation by taking the divergence of the Navier-Stokes equation and then projecting it onto the pressure POD modes. The pressure is then decomposed into lift and drag components and compared with the CFD results.
Akhtar, Imran [Virginia Tech, Department of Engineering Science and Mechanics, MC 0219, Blacksburg, VA (United States); Virginia Tech, Interdisciplinary Center for Applied Mathematics, MC 0531, Blacksburg, VA (United States); Nayfeh, Ali H. [Virginia Tech, Department of Engineering Science and Mechanics, MC 0219, Blacksburg, VA (United States); Ribbens, Calvin J. [Virginia Tech, Department of Computer Science, Blacksburg, VA (United States)
2009-07-15
Proper orthogonal decomposition (POD) has been used to develop a reduced-order model of the hydrodynamic forces acting on a circular cylinder. Direct numerical simulations of the incompressible Navier-Stokes equations have been performed using a parallel computational fluid dynamics (CFD) code to simulate the flow past a circular cylinder. Snapshots of the velocity and pressure fields are used to calculate the divergence-free velocity and pressure modes, respectively. We use the dominant of these velocity POD modes (a small number of eigenfunctions or modes) in a Galerkin procedure to project the Navier-Stokes equations onto a low-dimensional space, thereby reducing the distributed-parameter problem into a finite-dimensional nonlinear dynamical system in time. The solution of the reduced dynamical system is a limit cycle corresponding to vortex shedding. We investigate the stability of the limit cycle by using long-time integration and propose to use a shooting technique to home on the system limit cycle. We obtain the pressure-Poisson equation by taking the divergence of the Navier-Stokes equation and then projecting it onto the pressure POD modes. The pressure is then decomposed into lift and drag components and compared with the CFD results. (orig.)
Amsallem, David; Tezaur, Radek; Farhat, Charbel
2016-12-01
A comprehensive approach for real-time computations using a database of parametric, linear, projection-based reduced-order models (ROMs) based on arbitrary underlying meshes is proposed. In the offline phase of this approach, the parameter space is sampled and linear ROMs defined by linear reduced operators are pre-computed at the sampled parameter points and stored. Then, these operators and associated ROMs are transformed into counterparts that satisfy a certain notion of consistency. In the online phase of this approach, a linear ROM is constructed in real-time at a queried but unsampled parameter point by interpolating the pre-computed linear reduced operators on matrix manifolds and therefore computing an interpolated linear ROM. The proposed overall model reduction framework is illustrated with two applications: a parametric inverse acoustic scattering problem associated with a mockup submarine, and a parametric flutter prediction problem associated with a wing-tank system. The second application is implemented on a mobile device, illustrating the capability of the proposed computational framework to operate in real-time.
Middleborns disadvantaged? Testing birth-order effects on fitness in pre-industrial Finns.
Charlotte Faurie
Full Text Available Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle- and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first- or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition.
Jensen, Christian F S; Ohl, Dana A; Parker, Walter R
2015-01-01
OBJECTIVE: To investigate optimal test vial (TV) volume, utility and reliability of TVs, intermediate temperature exposure (-88°C to -93°C) before cryostorage, cryostorage in nitrogen vapor (VN2) and liquid nitrogen (LN2), and long-term stability of VN2 cryostorage of human semen. DESIGN: Prospec......OBJECTIVE: To investigate optimal test vial (TV) volume, utility and reliability of TVs, intermediate temperature exposure (-88°C to -93°C) before cryostorage, cryostorage in nitrogen vapor (VN2) and liquid nitrogen (LN2), and long-term stability of VN2 cryostorage of human semen. DESIGN...
Pecka, Shannon; Schmid, Kendra; Pozehl, Bunny
2014-12-01
This article describes development of the Pecka Grading Rubric (PGR) as a strategy to facilitate and evaluate students' higher-order thinking in discussion boards. The purpose of this study was to describe psychometric properties of the PGR. Rubric reliability was pilot tested on a discussion board assignment used by 15 senior student registered nurse anesthetist enrolled in an Advanced Principles of Anesthesia course. Interrater and intrarater reliabilities were tested using an interclass correlation coefficient (ICC) to evaluate absolute agreement of scoring. Raters gave each category a score, scores of the categories were summed, and a total score was calculated for the entire rubric. Interrater (ICC = 0.939, P < .001) and intrarater (ICC = 0.902 to 0.994, P < .001) reliabilities were excellent for total point scores. A content validity index was used to evaluate content validity. Raters evaluated content validity of each cell of the PGR. The content validity index (0.8-1.0) was acceptable. Known-group validity was evaluated by comparing graduate student registered nurse anesthetists (N = 7) with undergraduate senior nursing students (N = 13). Beginning evidence indicates a valid and reliable instrument that measures higher-order thinking in the student registered nurse anesthetist.
High-Order Fully General-Relativistic Hydrodynamics: new Approaches and Tests
Radice, David; Galeazzi, Filippo
2013-01-01
We present a new approach for achieving high-order convergence in fully general-relativistic hydrodynamic simulations. The approach is implemented in WhiskyTHC, a new code that makes use of state-of-the-art numerical schemes and was key in achieving, for the first time, higher than second-order convergence in the calculation of the gravitational radiation from inspiraling binary neutron stars Radice et al. (2013). Here, we give a detailed description of the algorithms employed and present results obtained for a series of classical tests involving isolated neutron stars. In addition, using the gravitational-wave emission from the late inspiral and merger of binary neutron stars, we make a detailed comparison between the results obtained with the new code and those obtained when using standard second-order schemes commonly employed for matter simulations in numerical relativity. We find that even at moderate resolutions and for binaries with large compactness, the phase accuracy is improved by a factor 50 or mo...
Hua, Changchun; Zhang, Liuliu; Guan, Xinping
2016-04-01
This paper studies the problem of output feedback control for a class of nonlinear time-delay systems with prescribed performance. The system is in the form of triangular structure with unmodelled dynamics. First, we introduce a reduced-order observer to provide the estimate of the unmeasured states. Then, by setting a new condition with the performance function, we design the state transformation with prescribed performance control. By employing backstepping method, we construct the output feedback controller. It is proved that the resulting closed-loop system is asymptotically stable and both transient and steady-state performance of the output are preserved with the changing supply function idea. Finally, a simulation example is conducted to show the effectiveness of the main results.
Yang, Yajie; Yang, Xiaojie; Yang, Wenyao; Li, Shibin; Xu, Jianhua; Jiang, Yadong
2014-01-01
In this paper, we demonstrated the utilization of reduced graphene oxide (RGO) Langmuir-Blodgett (LB) films as high performance hole injection layer in organic light-emitting diode (OLED). By using LB technique, the well-ordered and thickness-controlled RGO sheets are incorporated between the organic active layer and the transparent conducting indium tin oxide (ITO), leading to an increase of recombination between electrons and holes. Due to the dramatic increase of hole carrier injection efficiency in RGO LB layer, the device luminance performance is greatly enhanced comparable to devices fabricated with spin-coating RGO and a commercial conducting polymer PEDOT:PSS as the hole transport layer. Furthermore, our results indicate that RGO LB films could be an excellent alternative to commercial PEDOT:PSS as the effective hole transport and electron blocking layer in light-emitting diode devices.
Speeding-up the computation of high-lift aerodynamics using a residual-based reduced-order model
Mifsud, M.; Zimmermann, R.; Goertz, Stefan
2014-01-01
In this article, we propose a strategy for speeding-up the computation of the aerodynamics of industrial high-lift configurations using a residual-based reduced-order model (ROM). The ROM is based on the proper orthogonal decomposition (POD) of a set of solutions to the Navier–Stokes equations...... is augmented with the latest CFD computed flow solution. Using this strategy, a considerable reduction in the total number of iterations to reach the converged steady-state solution is achieved when compared with conventional computational techniques used in industry for a series of computations such as drag...... governing fluid flow at different parameter values, from which a set of orthogonal basis vectors is evaluated. By considering an initial set of few snapshots at different angles of attack, a ROM is constructed which is used to predict a solution at an angle of attack which is just outside the space spanned...
On the parameters identification of the Duffing's system by means of a reduced order observer
Mendoza-Camargo, Juan [CINVESTAV-IPN, Departamento de Control Automatico, Av. IPN 2508, A.P. 14740, Mexico, D.F. 07360 (Mexico); Aguilar-Iban-tilde ez, Carlos [CIC-IPN, Av. Juan de Dios Batiz s/n Esq. Manuel Othon de M., Unidad Profesional Adolfo Lopez Mateos, Col. San Pedro Zacatenco, A.P. 75476, Mexico, D.F. 07700 (Mexico)]. E-mail: caguilar@cic.ipn.mx; Martinez-Guerra, Rafael [CINVESTAV-IPN, Departamento de Control Automatico, Av. IPN 2508, A.P. 14740, Mexico, D.F. 07360 (Mexico)]. E-mail: rguerra@ctrl.cinvestav.mx; Garrido-Moctezuma, Ruben [CINVESTAV-IPN, Departamento de Control Automatico, Av. IPN 2508, A.P. 14740, Mexico, D.F. 07360 (Mexico)
2004-10-25
An on-line procedure for recovering the unknown parameters set of the Duffing's oscillator by means of a reduced order proportional integral observer is presented in this Letter. First, it is shown that the oscillator has the properties of being algebraically observable and algebraically identifiable with respect to a well-chosen output (which turns out to be the oscillator's position). Therefore, an extended differential parametrization of the output and its time derivatives can be obtained. This extended differential parametrization has the necessary information to estimate the output time derivatives and to recover the unknown parameters. The numerical implementation of this method is easily accomplished in a digital computer.
Amabili, M.; Sarkar, A.; Païdoussis, M. P.
2006-03-01
The geometric nonlinear response of a water-filled, simply supported circular cylindrical shell to harmonic excitation in the spectral neighbourhood of the fundamental natural frequency is investigated. The response is investigated for a fixed excitation frequency by using the excitation amplitude as bifurcation parameter for a wide range of variation. Bifurcation diagrams of Poincaré maps obtained from direct time integration and calculation of the Lyapunov exponents and Lyapunov dimension have been used to study the system. By increasing the excitation amplitude, the response undergoes (i) a period-doubling bifurcation, (ii) subharmonic response, (iii) quasi-periodic response and (iv) chaotic behaviour with up to 16 positive Lyapunov exponents (hyperchaos). The model is based on Donnell's nonlinear shallow-shell theory, and the reference solution is obtained by the Galerkin method. The proper orthogonal decomposition (POD) method is used to extract proper orthogonal modes that describe the system behaviour from time-series response data. These time-series have been obtained via the conventional Galerkin approach (using normal modes as a projection basis) with an accurate model involving 16 degrees of freedom (dofs), validated in previous studies. The POD method, in conjunction with the Galerkin approach, permits to build a lower-dimensional model as compared to those obtainable via the conventional Galerkin approach. Periodic and quasi-periodic response around the fundamental resonance for fixed excitation amplitude, can be very successfully simulated with a 3-dof reduced-order model. However, in the case of large variation of the excitation, even a 5-dof reduced-order model is not fully accurate. Results show that the POD methodology is not as "robust" as the Galerkin method.
Kikuchi, Ryota; Misaka, Takashi; Obayashi, Shigeru, E-mail: rkikuchi@edge.ifs.tohoku.ac.jp [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)
2015-10-15
An integrated method of a proper orthogonal decomposition based reduced-order model (ROM) and data assimilation is proposed for the real-time prediction of an unsteady flow field. In this paper, a particle filter (PF) and an ensemble Kalman filter (EnKF) are compared for data assimilation and the difference in the predicted flow fields is evaluated focusing on the probability density function (PDF) of the model variables. The proposed method is demonstrated using identical twin experiments of an unsteady flow field around a circular cylinder at the Reynolds number of 1000. The PF and EnKF are employed to estimate temporal coefficients of the ROM based on the observed velocity components in the wake of the circular cylinder. The prediction accuracy of ROM-PF is significantly better than that of ROM-EnKF due to the flexibility of PF for representing a PDF compared to EnKF. Furthermore, the proposed method reproduces the unsteady flow field several orders faster than the reference numerical simulation based on the Navier–Stokes equations. (paper)
Kikuchi, Ryota; Misaka, Takashi; Obayashi, Shigeru
2015-10-01
An integrated method of a proper orthogonal decomposition based reduced-order model (ROM) and data assimilation is proposed for the real-time prediction of an unsteady flow field. In this paper, a particle filter (PF) and an ensemble Kalman filter (EnKF) are compared for data assimilation and the difference in the predicted flow fields is evaluated focusing on the probability density function (PDF) of the model variables. The proposed method is demonstrated using identical twin experiments of an unsteady flow field around a circular cylinder at the Reynolds number of 1000. The PF and EnKF are employed to estimate temporal coefficients of the ROM based on the observed velocity components in the wake of the circular cylinder. The prediction accuracy of ROM-PF is significantly better than that of ROM-EnKF due to the flexibility of PF for representing a PDF compared to EnKF. Furthermore, the proposed method reproduces the unsteady flow field several orders faster than the reference numerical simulation based on the Navier-Stokes equations.
Investigations of trapped higher order modes using a 36-cell test structure
T. Weiland
1999-04-01
Full Text Available In future linear collider schemes, energy loss, as well as deterioration of the beam due to long-range wakefields, is a severe problem to be overcome. The wakefield effects in accelerator sections for these colliders are thought to be reduced either by damping, by detuning, or by a combination of both. While, in principle, damping is possible by selective coupling to dangerous higher order modes (HOMs, an alternative way is to prevent coherent excitation of these wakes by modifying a constant gradient accelerator tube in such a way that each following cell is progressively detuned in relation to the preceding ones (“detuned” or “stagger-tuned” structure. This should result in low transit time factors for the higher order modes. However, the disturbed longitudinal symmetry of the structure induces trapped modes especially in the lower dipole bands, which are again dangerous for the beam. The process of detuning suppresses the synchronous dipole modes with their extreme high loss factors, but it also produces many other HOMs with significant loss factors. Experimental results were compared with the predictions of MAFIA field calculations.
Gronostajski Z.
2015-06-01
Full Text Available This paper presents an analysis of the industrial process of hot forging a flange. The authors developed several thermomechanical models of the forging process for which they carried out computer simulations using the MSC.Marc 2013 software. In the Jawor Forge flanges with a neck are manufactured by hot forging in crank presses with a maximum load of 25 MN. The input material, in the form of a square bar, is heated up to a temperature of 1150°C and then formed in three operations: upsetting, preliminary die forging and finishing die forging. The main aim of the studies and the numerical analyses, in which the geometry of the tools would be modified, was to maximally reduce the amount of the input material taking into account the capabilities of the Jawor Forge, and consequently to significantly reduce the production costs. Besides the Forge’s equipment resources, the main constraint for modifications was the flange-with-neck forging standard which explicitely defines the tolerances for this element. The studies, which included numerical modelling, infrared measurements and technological tests, consisted in changing the geometry of the tools and that of the forging preform. As a result, the optimum direction for modifications aimed at reducing the mass of the input material was determined. The best of the solutions, making it possible to produce a correct forging in the Jawor Forge operating conditions, were adopted whereby the weight of the preform was reduced by 6.11%. Currently research is underway aimed at the application of the proposed and verified modifications to other flange forgings.
NASA Lewis Stirling SPRE testing and analysis with reduced number of cooler tubes
Wong, W.A.; Cairelli, J.E.; Swec, D.M.; Doeberling, T.J.; Lakatos, T.F. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Madi, F.J. [Sverdrup Technology, Inc., Cleveland, OH (United States). Lewis Research Center Group
1994-09-01
Free-piston Stirling power converters are a candidate for high capacity space power applications. The Space Power Research Engine (SPRE), a free-piston Stirling engine coupled with a linear alternator, is being tested at the NASA Lewis Research Center in support of the Civil Space Technology Initiative. The SPRE is used as a test bed for evaluating converter modifications which have the potential to improve converter performance and for validating computer code predictions. Reducing the number of cooler tubes on the SPRE has been identified as a modification with the potential to significantly improve power and efficiency. This paper describes experimental tests designed to investigate the effects of reducing the number of cooler tubes on converter power, efficiency and dynamics. Presented are test results from the converter operating with a reduced number of cooler tubes and comparisons between this data and both baseline test data and computer code predictions.
NASA Lewis Stirling SPRE testing and analysis with reduced number of cooler tubes
Wong, Wayne A.; Cairelli, James E.; Swec, Diane M.; Doeberling, Thomas J.; Lakatos, Thomas F.; Madi, Frank J.
1992-08-01
Free-piston Stirling power converters are candidates for high capacity space power applications. The Space Power Research Engine (SPRE), a free-piston Stirling engine coupled with a linear alternator, is being tested at the NASA Lewis Research Center in support of the Civil Space Technology Initiative. The SPRE is used as a test bed for evaluating converter modifications which have the potential to improve the converter performance and for validating computer code predictions. Reducing the number of cooler tubes on the SPRE has been identified as a modification with the potential to significantly improve power and efficiency. Experimental tests designed to investigate the effects of reducing the number of cooler tubes on converter power, efficiency and dynamics are described. Presented are test results from the converter operating with a reduced number of cooler tubes and comparisons between this data and both baseline test data and computer code predictions.
2012-01-01
reducing testing, from negative (delay or cancel patients’ surgeries), to indifference (little or no change in patient outcomes), to positive (save money, avoid unnecessary investigations) (Beliefs about consequences). Further, while most agreed that they are motivated to reduce ordering unnecessary tests (Motivation and goals), there was still a report of a gap between their motivation and practice (Behavioural regulation). Conclusion We identified key factors that anesthesiologists and surgeons believe influence whether they order pre-operative tests routinely for anesthesia management for a healthy adults undergoing low-risk surgery. These beliefs identify potential individual, team, and organisation targets for behaviour change interventions to reduce unnecessary routine test ordering. PMID:22682612
Patey, Andrea M; Islam, Rafat; Francis, Jill J; Bryson, Gregory L; Grimshaw, Jeremy M
2012-06-09
Routine pre-operative tests for anesthesia management are often ordered by both anesthesiologists and surgeons for healthy patients undergoing low-risk surgery. The Theoretical Domains Framework (TDF) was developed to investigate determinants of behaviour and identify potential behaviour change interventions. In this study, the TDF is used to explore anaesthesiologists' and surgeons' perceptions of ordering routine tests for healthy patients undergoing low-risk surgery. Sixteen clinicians (eleven anesthesiologists and five surgeons) throughout Ontario were recruited. An interview guide based on the TDF was developed to identify beliefs about pre-operative testing practices. Content analysis of physicians' statements into the relevant theoretical domains was performed. Specific beliefs were identified by grouping similar utterances of the interview participants. Relevant domains were identified by noting the frequencies of the beliefs reported, presence of conflicting beliefs, and perceived influence on the performance of the behaviour under investigation. Seven of the twelve domains were identified as likely relevant to changing clinicians' behaviour about pre-operative test ordering for anesthesia management. Key beliefs were identified within these domains including: conflicting comments about who was responsible for the test-ordering (Social/professional role and identity); inability to cancel tests ordered by fellow physicians (Beliefs about capabilities and social influences); and the problem with tests being completed before the anesthesiologists see the patient (Beliefs about capabilities and Environmental context and resources). Often, tests were ordered by an anesthesiologist based on who may be the attending anesthesiologist on the day of surgery while surgeons ordered tests they thought anesthesiologists may need (Social influences). There were also conflicting comments about the potential consequences associated with reducing testing, from negative
Patey Andrea M
2012-06-01
consequences associated with reducing testing, from negative (delay or cancel patients’ surgeries, to indifference (little or no change in patient outcomes, to positive (save money, avoid unnecessary investigations (Beliefs about consequences. Further, while most agreed that they are motivated to reduce ordering unnecessary tests (Motivation and goals, there was still a report of a gap between their motivation and practice (Behavioural regulation. Conclusion We identified key factors that anesthesiologists and surgeons believe influence whether they order pre-operative tests routinely for anesthesia management for a healthy adults undergoing low-risk surgery. These beliefs identify potential individual, team, and organisation targets for behaviour change interventions to reduce unnecessary routine test ordering.
Chase, Ivan D; Lindquist, W Brent
2016-01-01
The standard approach in accounting for hierarchical differentiation in biology and the social sciences considers a hierarchy as a static distribution of individuals possessing differing amounts of some valued commodity, assumes that the hierarchy is generated by micro-level processes involving individuals, and attempts to reverse engineer the processes that produced the hierarchy. However, sufficient experimental and analytical results are available to evaluate this standard approach in the case of animal dominance hierarchies (pecking orders). Our evaluation using evidence from hierarchy formation in small groups of both hens and cichlid fish reveals significant deficiencies in the three tenets of the standard approach in accounting for the organization of dominance hierarchies. In consequence, we suggest that a new approach is needed to explain the organization of pecking orders and, very possibly, by implication, for other kinds of social hierarchies. We develop an example of such an approach that considers dominance hierarchies to be dynamic networks, uses dynamic sequences of interaction (dynamic network motifs) to explain the organization of dominance hierarchies, and derives these dynamic sequences directly from observation of hierarchy formation. We test this dynamical explanation using computer simulation and find a good fit with actual dynamics of hierarchy formation in small groups of hens. We hypothesize that the same dynamic sequences are used in small groups of many other animal species forming pecking orders, and we discuss the data required to evaluate our hypothesis. Finally, we briefly consider how our dynamic approach may be generalized to other kinds of social hierarchies using the example of the distribution of empty gastropod (snail) shells occupied in populations of hermit crabs.
Ivan D Chase
Full Text Available The standard approach in accounting for hierarchical differentiation in biology and the social sciences considers a hierarchy as a static distribution of individuals possessing differing amounts of some valued commodity, assumes that the hierarchy is generated by micro-level processes involving individuals, and attempts to reverse engineer the processes that produced the hierarchy. However, sufficient experimental and analytical results are available to evaluate this standard approach in the case of animal dominance hierarchies (pecking orders. Our evaluation using evidence from hierarchy formation in small groups of both hens and cichlid fish reveals significant deficiencies in the three tenets of the standard approach in accounting for the organization of dominance hierarchies. In consequence, we suggest that a new approach is needed to explain the organization of pecking orders and, very possibly, by implication, for other kinds of social hierarchies. We develop an example of such an approach that considers dominance hierarchies to be dynamic networks, uses dynamic sequences of interaction (dynamic network motifs to explain the organization of dominance hierarchies, and derives these dynamic sequences directly from observation of hierarchy formation. We test this dynamical explanation using computer simulation and find a good fit with actual dynamics of hierarchy formation in small groups of hens. We hypothesize that the same dynamic sequences are used in small groups of many other animal species forming pecking orders, and we discuss the data required to evaluate our hypothesis. Finally, we briefly consider how our dynamic approach may be generalized to other kinds of social hierarchies using the example of the distribution of empty gastropod (snail shells occupied in populations of hermit crabs.
Levente Csoka
2008-02-01
Full Text Available Wheat straw (an agricultural by-product was pulped by an alkaline anthraquinone (AQ process. Then the straw pulp was treated by high-power ultrasound under different noble-gas (argon, krypton, xenon combinations. The pulps’ degree of beating and acid-insoluble lignin content were measured. Handsheets were made from sonicated and control pulps and tested for paper tensile strength. In this study we explore which noble-gas combination with ultrasound may be more useable to reduce the lignin content and enhance fibrillation. We also describe the most effective ultrasound-assisted, modified alkaline pulping process. Overall, we found that in two steps ultrasonification decreased the residual lignin contents more then 75 %, the pulp fibrillation increased from 12 to 70 °SR within 20 min. of ultrasound irradiation, and the tensile index of the handsheets increased by 65%. For sustainable paper production, it is required to develop alternative paper resources. Paper made from alternate fiber resources with efficient technology will improve our living standards without sacrificing the environment, our habitat. High frequency ultrasound-based pulp processing offers significant improvements, and it reduces energy and chemical consump-tions for pulp and paper production.
Boileau, Etienne; Pant, Sanjay; Roobottom, Carl; Sazonov, Igor; Deng, Jingjing; Xie, Xianghua; Nithiarasu, Perumal
2017-06-09
Image-based noninvasive fractional flow reserve (FFR) is an emergent approach to determine the functional relevance of coronary stenoses. The present work aimed to determine the feasibility of using a method based on coronary computed tomography angiography (CCTA) and reduced-order models (0D-1D) for the evaluation of coronary stenoses. The reduced-order methodology (cFFRRO ) was kept as simple as possible and did not include pressure drop or stenosis models. The geometry definition was incorporated into the physical model used to solve coronary flow and pressure. cFFRRO was assessed on a virtual cohort of 30 coronary artery stenoses in 25 vessels and compared with a standard approach based on 3D computational fluid dynamics (cFFR3D ). In this proof-of-concept study, we sought to investigate the influence of geometry and boundary conditions on the agreement between both methods. Performance on a per-vessel level showed a good correlation between both methods (Pearson's product-moment R=0.885, P<0.01), when using cFFR3D as the reference standard. The 95% limits of agreement were -0.116 and 0.08, and the mean bias was -0.018 (SD =0.05). Our results suggest no appreciable difference between cFFRRO and cFFR3D with respect to lesion length and/or aspect ratio. At a fixed aspect ratio, however, stenosis severity and shape appeared to be the most critical factors accounting for differences in both methods. Despite the assumptions inherent to the 1D formulation, asymmetry did not seem to affect the agreement. The choice of boundary conditions is critical in obtaining a functionally significant drop in pressure. Our initial data suggest that this approach may be part of a broader risk assessment strategy aimed at increasing the diagnostic yield of cardiac catheterisation for in-hospital evaluation of haemodynamically significant stenoses. Copyright © 2017 John Wiley & Sons, Ltd.
Cordier, Laurent; Tissot, Gilles; Noack, Bernd
2014-11-01
The aim of this communication is to demonstrate the use of Reduced-Order Model (ROM) based on Proper Orthogonal Decomposition (POD) to stabilize the flow over a circular cylinder in the laminar regime (Reynolds number equal to 60). The control is introduced by vertical oscillations of the cylinder, the objective being to determine by linear control the vertical velocity of the cylinder that stabilizes the flow. Since in Fluid-Structure Interaction, the POD algorithm cannot be applied directly, the fictitious domain method of Glowinski et al. (JMF 1999) is implemented where the solid domain is treated as a fluid undergoing an additional constraint. The POD-ROM is then classically obtained by projecting the Navier-Stokes equations on the first POD modes. The cylinder movement is enforced in the POD-ROM through the introduction of Lagrange multipliers. Finally, a Linear Quadratic Regulator framework is used to determine the optimal control law such that the flow is stabilized. Partially funded by the ANR Chair of Excellence TUCOROM and the Carnot project INTACOO.
Caiazzo, A; Caforio, Federica; Montecinos, Gino; Muller, Lucas O; Blanco, Pablo J; Toro, Eluterio F
2016-10-25
This work presents a detailed investigation of a parameter estimation approach on the basis of the reduced-order unscented Kalman filter (ROUKF) in the context of 1-dimensional blood flow models. In particular, the main aims of this study are (1) to investigate the effects of using real measurements versus synthetic data for the estimation procedure (i.e., numerical results of the same in silico model, perturbed with noise) and (2) to identify potential difficulties and limitations of the approach in clinically realistic applications to assess the applicability of the filter to such setups. For these purposes, the present numerical study is based on a recently published in vitro model of the arterial network, for which experimental flow and pressure measurements are available at few selected locations. To mimic clinically relevant situations, we focus on the estimation of terminal resistances and arterial wall parameters related to vessel mechanics (Young's modulus and wall thickness) using few experimental observations (at most a single pressure or flow measurement per vessel). In all cases, we first perform a theoretical identifiability analysis on the basis of the generalized sensitivity function, comparing then the results owith the ROUKF, using either synthetic or experimental data, to results obtained using reference parameters and to available measurements.
Lijun Zhang
2015-01-01
Full Text Available Brake squeal is often analytically studied by a complex eigenvalue analysis of linearized models of the brake assembly that is usually quite large. In this paper, a method for determining those frequencies having the most effect on the pair of coupling frequencies that saves much time is put forward and a reduced-order model is presented based on the complex modes theory. The reduced-order model is proved to be effective when applied to a flexible pin-on-disc system; even damping and nonlinearity are taken into consideration. This reduced-order model can predict the onset of squeal as well as the squeal frequency with sufficient accuracy and largely reduced amount of calculation and gives us a practical guide to perform design optimization in order to reduce brake squeal.
Reduced Test Pattern Generation of Multiple SIC Vectors with Input and Output Delay Faults
P.T.Sairam
2014-11-01
Full Text Available In recent years, the design for low power has become one of the greatest challenges in high-performance very large scale integration (VLSI design. Most of the methods focus on the power consumption during normal mode operation, while test mode operation has not normally been a predominant concern. However, it has been found that the power consumed during test mode operation is often much higher than during normal mode operation [1]. This is because most of the consumed power results from the switching activity in the nodes of the circuit under test (CUT, which is much higher during test mode than during normal mode operation [1]–[3]. In the proposed pattern, each generated vector applied to each scan chain is an SIC vector, which can minimize the input transition and reduce test power. In VLSI testing, power reduction is achieved by increasing the correlation between consecutive test patterns.
Mishra, Srikanta; Jin, Larry; He, Jincong; Durlofsky, Louis
2015-06-30
Reduced-order models provide a means for greatly accelerating the detailed simulations that will be required to manage CO_{2} storage operations. In this work, we investigate the use of one such method, POD-TPWL, which has previously been shown to be effective in oil reservoir simulation problems. This method combines trajectory piecewise linearization (TPWL), in which the solution to a new (test) problem is represented through a linearization around the solution to a previously-simulated (training) problem, with proper orthogonal decomposition (POD), which enables solution states to be expressed in terms of a relatively small number of parameters. We describe the application of POD-TPWL for CO_{2}-water systems simulated using a compositional procedure. Stanford’s Automatic Differentiation-based General Purpose Research Simulator (AD-GPRS) performs the full-order training simulations and provides the output (derivative matrices and system states) required by the POD-TPWL method. A new POD-TPWL capability introduced in this work is the use of horizontal injection wells that operate under rate (rather than bottom-hole pressure) control. Simulation results are presented for CO_{2} injection into a synthetic aquifer and into a simplified model of the Mount Simon formation. Test cases involve the use of time-varying well controls that differ from those used in training runs. Results of reasonable accuracy are consistently achieved for relevant well quantities. Runtime speedups of around a factor of 370 relative to full- order AD-GPRS simulations are achieved, though the preprocessing needed for POD-TPWL model construction corresponds to the computational requirements for about 2.3 full-order simulation runs. A preliminary treatment for POD-TPWL modeling in which test cases differ from training runs in terms of geological parameters (rather than well controls) is also presented. Results in this case involve only small differences between
Niche evolution and adaptive radiation: Testing the order of trait divergence
Ackerly, D.D.; Schwilk, D.W.; Webb, C.O.
2006-01-01
In the course of an adaptive radiation, the evolution of niche parameters is of particular interest for understanding modes of speciation and the consequences for coexistence of related species within communities. We pose a general question: In the course of an evolutionary radiation, do traits related to within-community niche differences (?? niche) evolve before or after differentiation of macrohabitat affinity or climatic tolerances (?? niche)? Here we introduce a new test to address this question, based on a modification of the method of independent contrasts. The divergence order test (DOT) is based on the average age of the nodes on a tree, weighted by the absolute magnitude of the contrast at each node for a particular trait. The comparison of these weighted averages reveals whether large divergences for one trait have occurred earlier or later in the course of diversification, relative to a second trait; significance is determined by bootstrapping from maximum-likelihood ancestral state reconstructions. The method is applied to the evolution of Ceanothus, a woody plant group in California, in which co-occurring species exhibit significant differences in a key leaf trait (specific leaf area) associated with contrasting physiological and life history strategies. Co-occurring species differ more for this trait than expected under a null model of community assembly. This ?? niche difference evolved early in the divergence of two major subclades within Ceanothus, whereas climatic distributions (?? niche traits) diversified later within each of the subclades. However, rapid evolution of climate parameters makes inferences of early divergence events highly uncertain, and differentiation of the ?? niche might have taken place throughout the evolution of the group, without leaving a clear phylogenetic signal. Similar patterns observed in several plant and animal groups suggest that early divergence of ?? niche traits might be a common feature of niche evolution in
Denton, Mark A. [AREVA Federal Services, Charlotte, NC (United States)
2016-01-19
Under Task Order 22 of the industry Advisory and Assistance Services (A&AS) Contract to the Department of Energy (DOE) DE-NE0000291, AREVA has been tasked with providing assistance with engineering, analysis, cost estimating, and design support of a system for disposal of radioactive wastes in deep boreholes (without the use of radioactive waste). As part of this task order, AREVA was requested, through a letter of technical direction, to evaluate Sandia National Laboratory’s (SNL’s) waste package borehole emplacement system concept recommendation using input from DOE and SNL. This summary review report (SRR) documents this evaluation, with its focus on the primary input document titled: “Deep Borehole Field Test Specifications/M2FT-15SN0817091” Rev. 1 [1], hereafter referred to as the “M2 report.” The M2 report focuses on the conceptual design development for the Deep Borehole Field Test (DBFT), mainly the test waste packages (WPs) and the system for demonstrating emplacement and retrieval of those packages in the Field Test Borehole (FTB). This SRR follows the same outline as the M2 report, which allows for easy correlation between AREVA’s review comments, discussion, potential proposed alternatives, and path forward with information established in the M2 report. AREVA’s assessment focused on three primary elements of the M2 report: the conceptual design of the WPs proposed for deep borehole disposal (DBD), the mode of emplacement of the WP into DBD, and the conceptual design of the DBFT. AREVA concurs with the M2 report’s selection of the wireline emplacement mode specifically over the drill-string emplacement mode and generically over alternative emplacement modes. Table 5-1 of this SRR compares the pros and cons of each emplacement mode considered viable for DBD. The primary positive characteristics of the wireline emplacement mode include: (1) considered a mature technology; (2) operations are relatively simple; (3) probability of a
Denton, Mark A. [AREVA Federal Services, Charlotte, NC (United States)
2016-01-19
Under Task Order 22 of the industry Advisory and Assistance Services (A&AS) Contract to the Department of Energy (DOE) DE-NE0000291, AREVA has been tasked with providing assistance with engineering, analysis, cost estimating, and design support of a system for disposal of radioactive wastes in deep boreholes (without the use of radioactive waste). As part of this task order, AREVA was requested, through a letter of technical direction, to evaluate Sandia National Laboratory’s (SNL’s) waste package borehole emplacement system concept recommendation using input from DOE and SNL. This summary review report (SRR) documents this evaluation, with its focus on the primary input document titled: “Deep Borehole Field Test Specifications/M2FT-15SN0817091” Rev. 1 [1], hereafter referred to as the “M2 report.” The M2 report focuses on the conceptual design development for the Deep Borehole Field Test (DBFT), mainly the test waste packages (WPs) and the system for demonstrating emplacement and retrieval of those packages in the Field Test Borehole (FTB). This SRR follows the same outline as the M2 report, which allows for easy correlation between AREVA’s review comments, discussion, potential proposed alternatives, and path forward with information established in the M2 report. AREVA’s assessment focused on three primary elements of the M2 report: the conceptual design of the WPs proposed for deep borehole disposal (DBD), the mode of emplacement of the WP into DBD, and the conceptual design of the DBFT. AREVA concurs with the M2 report’s selection of the wireline emplacement mode specifically over the drill-string emplacement mode and generically over alternative emplacement modes. Table 5-1 of this SRR compares the pros and cons of each emplacement mode considered viable for DBD. The primary positive characteristics of the wireline emplacement mode include: (1) considered a mature technology; (2) operations are relatively simple; (3) probability of a
N' Diaye, Mamadou; Pueyo, Laurent; Soummer, Rémi, E-mail: mamadou@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2015-02-01
The Apodized Pupil Lyot Coronagraph (APLC) is a diffraction suppression system installed in the recently deployed instruments Palomar/P1640, Gemini/GPI, and VLT/SPHERE to allow direct imaging and spectroscopy of circumstellar environments. Using a prolate apodization, the current implementations offer raw contrasts down to 10{sup –7} at 0.2 arcsec from a star over a wide bandpass (20%), in the presence of central obstruction and struts, enabling the study of young or massive gaseous planets. Observations of older or lighter companions at smaller separations would require improvements in terms of the inner working angle (IWA) and contrast, but the methods originally used for these designs were not able to fully explore the parameter space. We propose a novel approach to improve the APLC performance. Our method relies on the linear properties of the coronagraphic electric field with the apodization at any wavelength to develop numerical solutions producing coronagraphic star images with high-contrast region in broadband light. We explore the parameter space by considering different aperture geometries, contrast levels, dark-zone sizes, bandpasses, and focal plane mask sizes. We present an application of these solutions to the case of Gemini/GPI with a design delivering a 10{sup –8} raw contrast at 0.19 arcsec and offering a significantly reduced sensitivity to low-order aberrations compared to the current implementation. Optimal solutions have also been found to reach 10{sup –10} contrast in broadband light regardless of the aperture shape, with effective IWA in the 2-3.5 λ/D range, therefore making the APLC a suitable option for the future exoplanet direct imagers on the ground or in space.
Pan, Lehua [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oldenburg, Curtis M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2017-07-26
Potential CO_{2} leakage through existing open wellbores is one of the most significant hazards that need to be addressed in geologic carbon sequestration (GCS) projects. In the framework of the National Risk Assessment Partnership (NRAP) which requires fast computations for uncertainty analysis, rigorous simulation of the coupled wellbore-reservoir system is not practical. We have developed a 7,200-point look-up table reduced-order model (ROM) for estimating the potential leakage rate up open wellbores in response to CO_{2} injection nearby. The ROM is based on coupled simulations using T2Well/ECO2H which was run repeatedly for representative conditions relevant to NRAP to create a look-up table response-surface ROM. The ROM applies to a wellbore that fully penetrates a 20-m thick reservoir that is used for CO_{2} storage. The radially symmetric reservoir is assumed to have initially uniform pressure, temperature, gas saturation, and brine salinity, and it is assumed these conditions are held constant at the far-field boundary (100 m away from the wellbore). In such a system, the leakage can quickly reach quasi-steady state. The ROM table can be used to estimate both the free-phase CO_{2} and brine leakage rates through an open well as a function of wellbore and reservoir conditions. Results show that injection-induced pressure and reservoir gas saturation play important roles in controlling leakage. Caution must be used in the application of this ROM because well leakage is formally transient and the ROM lookup table was populated using quasi-steady simulation output after 1000 time steps which may correspond to different physical times for the various parameter combinations of the coupled wellbore-reservoir system.
Effects of Reducing the Cognitive Load of Mathematics Test Items on Student Performance
Susan C. Gillmor
2015-01-01
Full Text Available This study explores a new item-writing framework for improving the validity of math assessment items. The authors transfer insights from Cognitive Load Theory (CLT, traditionally used in instructional design, to educational measurement. Fifteen, multiple-choice math assessment items were modified using research-based strategies for reducing extraneous cognitive load. An experimental design with 222 middle-school students tested the effects of the reduced cognitive load items on student performance and anxiety. Significant findings confirm the main research hypothesis that reducing the cognitive load of math assessment items improves student performance. Three load-reducing item modifications are identified as particularly effective for reducing item difficulty: signalling important information, aesthetic item organization, and removing extraneous content. Load reduction was not shown to impact student anxiety. Implications for classroom assessment and future research are discussed.
Grier Thomas J
2006-02-01
Full Text Available Abstract Background Avoidance of allergens is still recommended as the first and best way to prevent allergic illnesses and their comorbid diseases. Despite a variety of attempts there has been very limited success in the area of environmental control of allergic disease. Our objective was to identify a non-invasive, non-pharmacological method to reduce indoor allergen loads in atopic persons' homes and public environments. We employed a novel in vivo approach to examine the possibility of using aluminum sulfate to control environmental allergens. Methods Fifty skin test reactive patients were simultaneously skin tested with conventional test materials and the actions of the protein/glycoprotein modifier, aluminum sulfate. Common allergens, dog, cat, dust mite, Alternaria, and cockroach were used in the study. Results Skin test reactivity was significantly reduced by the modifier aluminum sulfate. Our studies demonstrate that the effects of histamine were not affected by the presence of aluminum sulfate. In fact, skin test reactivity was reduced independent of whether aluminum sulfate was present in the allergen test material or removed prior to testing, indicating that the allergens had in some way been inactivated. Conclusion Aluminum sulfate was found to reduce the in vivo allergic reaction cascade induced by skin testing with common allergens. The exact mechanism is not clear but appears to involve the alteration of IgE-binding epitopes on the allergen. Our results indicate that it may be possible to diminish the allergenicity of an environment by application of the active agent aluminum sulfate, thus producing environmental control without complete removal of the allergen.
2010-07-01
... and mixtures with Chemical Abstract Service Registry Numbers. 799.5000 Section 799.5000 Protection of... Testing consent orders for substances and mixtures with Chemical Abstract Service Registry Numbers. This... adopted under 40 CFR part 790. Listed below in Chemical Abstract Service (CAS) Registry Number order...
Korte, S.M.; de Kloet, E.R.; Buwalda, B; Bouman, S.D.; Bohus, B
1996-01-01
Immobility time of rats in the forced swim test was reduced after bilateral infusion of an 18-mer antisense phosphorothioate oligodeoxynucleotide targeted to the glucocorticoid receptor mRNA into the dentate gyrus of the hippocampus. Vehicle-, sense- and scrambled sequence-treated animals spent
MapReduce for information retrieval evaluation: "Let's quickly test this on 12 TB of data"
Hiemstra, Djoerd; Hauff, Claudia; Agosti, Maristella; Ferro, Nicola; Peters, Carol; Rijke, de Maarten; Smeaton, Alan
2010-01-01
We propose to use MapReduce to quickly test new retrieval approaches on a cluster of machines by sequentially scanning all documents. We present a small case study in which we use a cluster of 15 low cost machines to search a web crawl of 0.5 billion pages showing that sequential scanning is a viabl
Korte, S.M.; de Kloet, E.R.; Buwalda, B; Bouman, S.D.; Bohus, B
1996-01-01
Immobility time of rats in the forced swim test was reduced after bilateral infusion of an 18-mer antisense phosphorothioate oligodeoxynucleotide targeted to the glucocorticoid receptor mRNA into the dentate gyrus of the hippocampus. Vehicle-, sense- and scrambled sequence-treated animals spent sign
Reducing Test Anxiety among Third Grade Students through the Implementation of Relaxation Techniques
Larson, Heidi A.; El Ramahi, Mera K.; Conn, Steven R.; Estes, Lincoln A.; Ghibellini, Amanda B.
2010-01-01
The purpose of this study was to reduce the negative effects that self-perceived levels of test anxiety have on third-grade students. The participants in this study consisted of 177 third-grade students at two Midwestern public elementary schools. Students at one school were taught relaxation techniques, while students at the second school served…
Main, C; Moxham, T; Wyatt, J C; Kay, J; Anderson, R; Stein, K
2010-10-01
Order communication systems (OCS) are computer applications used to enter diagnostic and therapeutic patient care orders and to view test results. Many potential benefits of OCS have been identified including improvements in clinician ordering patterns, optimisation of clinical time, and aiding communication processes between clinicians and different departments. Many OCS now include computerised decision support systems (CDSS), which are information systems designed to improve clinical decision-making. CDSS match individual patient characteristics to a computerised knowledge base, and software algorithms generate patient-specific recommendations. To investigate which CDSS in OCS are in use within the UK and the impact of CDSS in OCS for diagnostic, screening or monitoring test ordering compared to OCS without CDSS. To determine what features of CDSS are associated with clinician or patient acceptance of CDSS in OCS and what is known about the cost-effectiveness of CDSS in diagnostic, screening or monitoring test OCS compared to OCS without CDSS. A generic search to identify potentially relevant studies for inclusion was conducted using MEDLINE, EMBASE, Cochrane Controlled Trials Register (CCTR), CINAHL (Cumulative Index to Nursing and Allied Health Literature), DARE (Database of Abstracts of Reviews of Effects), Health Technology Assessment (HTA) database, IEEE (Institute of Electrical and Electronic Engineers) Xplore digital library, NHS Economic Evaluation Database (NHS EED) and EconLit, searched between 1974 and 2009 with a total of 22,109 titles and abstracts screened for inclusion. CDSS for diagnostic, screening and monitoring test ordering OCS in use in the UK were identified through contact with the 24 manufacturers/suppliers currently contracted by the National Project for Information Technology (NpfIT) to provide either national or specialist decision support. A generic search to identify potentially relevant studies for inclusion in the review was
Reducing the harmful effects of alcohol misuse: the ethics of sobriety testing in criminal justice.
Shaw, David; McCluskey, Karyn; Linden, Will; Goodall, Christine
2012-11-01
Alcohol use and abuse play a major role in both crime and negative health outcomes in Scotland. This paper provides a description and ethical and legal analyses of a novel remote alcohol monitoring scheme for offenders which seeks to reduce alcohol-related harm to both the criminal and the public. It emerges that the prospective benefits of this scheme to health and public order vastly outweigh any potential harms.
Karam, Ayman M.
2016-12-01
Membrane Distillation (MD) is an emerging sustainable desalination technique. While MD has many advantages and can be powered by solar thermal energy, its main drawback is the low water production rate. However, the MD process has not been fully optimized in terms of its manipulated and controlled variables. This is largely due to the lack of adequate dynamic models to study and simulate the process. In addition, MD is prone to membrane fouling, which is a fault that degrades the performance of the MD process. This work has three contributions to address these challenges. First, we derive a mathematical model of Direct Contact Membrane Distillation (DCMD), which is the building block for the next parts. Then, the proposed model is extended to account for membrane fouling and an observer-based fouling detection method is developed. Finally, various control strategies are implemented to optimize the performance of the DCMD solar-powered process. In part one, a reduced-order dynamic model of DCMD is developed based on lumped capacitance method and electrical analogy to thermal systems. The result is an electrical equivalent thermal network to the DCMD process, which is modeled by a system of nonlinear differential algebraic equations (DAEs). This model predicts the water-vapor flux and the temperature distribution along the module length. Experimental data is collected to validate the steady-state and dynamic responses of the proposed model, with great agreement demonstrated in both. The second part proposes an extension of the model to account for membrane fouling. An adaptive observer for DAE systems is developed and convergence proof is presented. A method for membrane fouling detection is then proposed based on adaptive observers. Simulation results demonstrate the performance of the membrane fouling detection method. Finally, an optimization problem is formulated to maximize the process efficiency of a solar-powered DCMD. The adapted method is known as Extremum
Love, Sara A; McKinney, Zeke J; Sandoval, Yader; Smith, Stephen W; Kohler, Rebecca; Murakami, MaryAnn M; Apple, Fred S
2015-03-01
We assessed the utilization rationale behind provider ordering of cardiac troponin I (cTnI) testing for the diagnosis of myocardial infarction after implementation of a hospital-wide serial order protocol. During 2 months in 2013, any request for additional cTnI testing within 30 days of the initial serial cTnI order prompted an electronic health record best practice alert (BPA), which included clinical decision support that could be bypassed by giving a clinical indication. cTnI orders were not limited (timing, number), and upon BPA, trigger data was collected for clinical indications and actions, patient stay (duration, location), International Classification of Diseases, Revision 9 diagnosis, cTnI orders, and timing of cTnI measurements. The BPA was triggered 1477 times by 423 providers who cared for 702 patients. There were a mean of 3.6 cTnI results per patient, 2.1 BPAs per patient, and 1.2 visits per patient. Providers (42% of whom were residents) acknowledged and overrode the BPA 97% of the time. In response to the BPA, 65% of providers selected a prepared rationale: 64% acute coronary syndrome/ST-elevation myocardial infarction/non-ST-elevation myocardial infarction; 30% demand ischemia; and 6% non-ACS myocardial necrosis. Of the remaining 35% of providers, 71% listed no rationale for their additional cTnI orders. Of patients with a BPA, 93% had non-ACS-related primary International Classification of Diseases, Revision 9 diagnosis, and 58% of the time, patients' cTnI results never increased during their stay. In 53% of cases, BPAs were generated by a request for an additional cTnI series when <2 results were available. Providers largely ignored the BPA that warned of potential overutilization of cTnI testing independent of diagnosis, including ACS. © 2014 American Association for Clinical Chemistry.
Testing the Pecking Order Theory: The Impact of Financing Surpluses and Large Financing Deficits
A. de Jong (Abe); M.J.C.M. Verbeek (Marno); P. Verwijmeren (Patrick)
2007-01-01
textabstractThis paper extends the basic pecking order model of Shyam-Sunder and Myers (1999) by separating the effects of financing surpluses, normal deficits, and large deficits. Using a broad cross-section of publicly traded firms for 1971 to 2005, we find that the estimated pecking order coeffic
The Impact of Financing Surpluses and Large Financing Deficits on Tests of the Pecking Order Theory
de Jong, Abe; Verbeek, Marno; Verwijmeren, Patrick
2010-01-01
This paper extends the basic pecking order model of Shyam-Sunder and Myers by separating the effects of financing surpluses, normal deficits, and large deficits. Using a panel of US firms over the period 1971-2005, we find that the estimated pecking order coefficient is highest for surpluses (0.90),
Not All Order Memory Is Equal: Test Demands Reveal Dissociations in Memory for Sequence Information
Jonker, Tanya R.; MacLeod, Colin M.
2017-01-01
Remembering the order of a sequence of events is a fundamental feature of episodic memory. Indeed, a number of formal models represent temporal context as part of the memory system, and memory for order has been researched extensively. Yet, the nature of the code(s) underlying sequence memory is still relatively unknown. Across 4 experiments that…
A test of first order scaling in Nf =2 QCD: a progress report
Bonati, C; D'Elia, M; Di Giacomo, A; Pica, C
2008-01-01
We present the status of our analysis on the order of the finite temperature transition in QCD with two flavors of degenerate fermions. Our new simulations on large lattices support the hypothesis of the first order nature of the transition, showing a preliminary two state signal. We will discuss the implications and the next steps in our analysis.
Not All Order Memory Is Equal: Test Demands Reveal Dissociations in Memory for Sequence Information
Jonker, Tanya R.; MacLeod, Colin M.
2017-01-01
Remembering the order of a sequence of events is a fundamental feature of episodic memory. Indeed, a number of formal models represent temporal context as part of the memory system, and memory for order has been researched extensively. Yet, the nature of the code(s) underlying sequence memory is still relatively unknown. Across 4 experiments that…
2013-12-26
... AGENCY 12 CFR Part 1238 Orders: Reporting by Regulated Entities of Stress Testing Results as of September... controls, that their operations and activities foster liquid, efficient, competitive, and resilient... prescribe for the regulated entities the scenarios to be used for stress testing. The Summary Instructions...
Schmelter, Dirk; Hintze-Bruening, Horst
2016-06-29
Graphene oxide (GO) dispersed in water has been combined with a mixture of aqueous polymer dispersions and melamine formaldehyde resin (MF). Stable low viscous fluids with no obvious signs of mesoscale ordering at 0.3 wt % yield transparent films with GO loadings up to one weight percent in the form of homogeneously aligned double strands, each comprising few individual layers of the carbon allotrope. While baking of the films at 160 °C results in minor thermal reduction of GO, in situ reduction with excess hydroxylamine (HA) in the presence of the polymer colloids yields stable dispersions in which amphiphilic graphene like flakes temporarily encapsulate gaseous reaction products. Depending on the parameters in the time-temperature domain, the hollow spheres may be transferred into solid material or disassemble during film formation, the latter case providing black, smooth, and transparent films with up to eight magnitudes increased electrical conductivity and an oxygen permeability 30-fold higher compared to the neat polymer matrix. In contrast, GO reduces oxygen permeability by that factor, while water permeability stays unchanged. Thermo-mechanical measurements reveal matrix stiffening by the platelets as well as by HA, the latter via modifying the MF reactivity. Excellent stone chip resistance and ballistic impact tests demonstrate efficient energy dissipation and crack deflection provided by the laminate like morphology of GO based composite. On the contrary, the same material only provides moderate substrate protection in rain erosion tests.
Opportunities and strategies to further reduce animal use for Leptospira vaccine potency testing.
Walker, A; Srinivas, G B
2013-09-01
Hamsters are routinely infected with virulent Leptospira for two purposes in the regulation of biologics: the performance of Codified potency tests and maintenance of challenge culture for the Codified potency tests. Options for reducing animal use in these processes were explored in a plenary lecture at the "International Workshop on Alternative Methods for Leptospira Vaccine Potency Testing: State of the Science and the Way Forward" held at the Center for Veterinary Biologics in September 2012. The use of validated in vitro potency assays such as those developed by the U.S. Department of Agriculture for Leptospira (L.) canicola, Leptospira grippotyphosa, Leptospira pomona, and Leptospira icterohaemorrhagiae rather than the Codified hamster vaccination-challenge assay was encouraged. Alternatives such as reduced animal numbers in the hamster vaccination-challenge testing were considered for problematic situations. Specifically, the merits of sharing challenge controls, reducing group sizes, and eliminating animals for concurrent challenge dose titration were assessed. Options for maintaining virulent, stable cultures without serial passage through hamsters or with decreased hamster use were also discussed. The maintenance of virulent Leptospira without the use of live animals is especially difficult since a reliable means to maintain virulence after multiple in vitro passages has not yet been identified. Published by Elsevier Ltd.
Design and test of aircraft engine isolators for reduced interior noise
Unruh, J. F.; Scheidt, D. C.
1982-01-01
Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.
Proceedings of the 1988 International Meeting on Reduced Enrichment for Research and Test Reactors
1993-07-01
The international effort to develop and implement new research reactor fuels utilizing low-enriched uranium, instead of highly- enriched uranium, continues to make solid progress. This effort is the cornerstone of a widely shared policy aimed at reducing, and possibly eliminating, international traffic in highly-enriched uranium and the nuclear weapon proliferation concerns associated with this traffic. To foster direct communication and exchange of ideas among the specialists in this area, the Reduced Enrichment Research and Test Reactor (RERTR) Program, at Argonne National Laboratory, sponsored this meeting as the eleventh of a series which began 1978. Individual papers presented at the meeting have been cataloged separately.
Interpolated memory tests reduce mind wandering and improve learning of online lectures.
Szpunar, Karl K; Khan, Novall Y; Schacter, Daniel L
2013-04-16
The recent emergence and popularity of online educational resources brings with it challenges for educators to optimize the dissemination of online content. Here we provide evidence that points toward a solution for the difficulty that students frequently report in sustaining attention to online lectures over extended periods. In two experiments, we demonstrate that the simple act of interpolating online lectures with memory tests can help students sustain attention to lecture content in a manner that discourages task-irrelevant mind wandering activities, encourages task-relevant note-taking activities, and improves learning. Importantly, frequent testing was associated with reduced anxiety toward a final cumulative test and also with reductions in subjective estimates of cognitive demand. Our findings suggest a potentially key role for interpolated testing in the development and dissemination of online educational content.
Reducing patient identification errors related to glucose point-of-care testing
Gaurav Alreja
2011-01-01
Full Text Available Background: Patient identification (ID errors in point-of-care testing (POCT can cause test results to be transferred to the wrong patient′s chart or prevent results from being transmitted and reported. Despite the implementation of patient barcoding and ongoing operator training at our institution, patient ID errors still occur with glucose POCT. The aim of this study was to develop a solution to reduce identification errors with POCT. Materials and Methods: Glucose POCT was performed by approximately 2,400 clinical operators throughout our health system. Patients are identified by scanning in wristband barcodes or by manual data entry using portable glucose meters. Meters are docked to upload data to a database server which then transmits data to any medical record matching the financial number of the test result. With a new model, meters connect to an interface manager where the patient ID (a nine-digit account number is checked against patient registration data from admission, discharge, and transfer (ADT feeds and only matched results are transferred to the patient′s electronic medical record. With the new process, the patient ID is checked prior to testing, and testing is prevented until ID errors are resolved. Results: When averaged over a period of a month, ID errors were reduced to 3 errors/month (0.015% in comparison with 61.5 errors/month (0.319% before implementing the new meters. Conclusion: Patient ID errors may occur with glucose POCT despite patient barcoding. The verification of patient identification should ideally take place at the bedside before testing occurs so that the errors can be addressed in real time. The introduction of an ADT feed directly to glucose meters reduced patient ID errors in POCT.
Clarke, M. S.; Prendergast, M. A.; Terry, A. V. Jr
1999-01-01
A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the beta-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [3H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [3H]NE release. The compound (800-2400 microg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with 14C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod
Santos-Galduróz, R F; Oliveira, F G; Galduróz, J C F; Bueno, O F A
2009-10-01
The influence of aging on memory has been extensively studied, but the importance of short-term memory and recall sequence has not. The objective of the current study was to examine the recall order of words presented on lists and to determine if age affects recall sequence. Physically and psychologically healthy male subjects were divided into two groups according to age, i.e., 23 young subjects (20 to 30 years) and 50 elderly subjects (60 to 70 years) submitted to the Wechsler Adult Intelligence Scale-Revised and the free word recall test. The order of word presentation significantly affected the 3rd and 4th words recalled (P recalled the last words presented from each list (words 13-15) significantly more times 3rd and 4th than words presented in all remaining positions (P word presentation also significantly affected the 5th and 6th words recalled (P = 0.05; F = 7.5) and there was a significant interaction between the order of presentation and the type of list presented (P < 0.01; F = 20.8). The more developed the cognitive functions, resulting mainly from formal education, the greater the cognitive reserve, helping to minimize the effects of aging on the long-term memory (episodic declarative).
Elmunzer, B Joseph; Singal, Amit G; Sussman, Jeremy B; Deshpande, Amar R; Sussman, Daniel A; Conte, Marisa L; Dwamena, Ben A; Rogers, Mary A M; Schoenfeld, Philip S; Inadomi, John M; Saini, Sameer D; Waljee, Akbar K
2015-03-01
Comparative effectiveness data pertaining to competing colorectal cancer (CRC) screening tests do not exist but are necessary to guide clinical decision making and policy. To perform a comparative synthesis of clinical outcomes studies evaluating the effects of competing tests on CRC-related mortality. Traditional and network meta-analyses. Two reviewers identified studies evaluating the effect of guaiac-based fecal occult blood testing (gFOBT), flexible sigmoidoscopy (FS), or colonoscopy on CRC-related mortality. gFOBT, FS, colonoscopy. Traditional meta-analysis was performed to produce pooled estimates of the effect of each modality on CRC mortality. Bayesian network meta-analysis (NMA) was performed to indirectly compare the effectiveness of screening modalities. Multiple sensitivity analyses were performed. Traditional meta-analysis revealed that, compared with no intervention, colonoscopy reduced CRC-related mortality by 57% (relative risk [RR] 0.43; 95% confidence interval [CI], 0.33-0.58), whereas FS reduced CRC-related mortality by 40% (RR 0.60; 95% CI, 0.45-0.78), and gFOBT reduced CRC-related mortality by 18% (RR 0.82; 95% CI, 0.76-0.88). NMA demonstrated nonsignificant trends favoring colonoscopy over FS (RR 0.71; 95% CI, 0.45-1.11) and FS over gFOBT (RR 0.74; 95% CI, 0.51-1.09) for reducing CRC-related deaths. NMA-based simulations, however, revealed that colonoscopy has a 94% probability of being the most effective test for reducing CRC mortality and a 99% probability of being most effective when the analysis is restricted to screening studies. Randomized trials and observational studies were combined within the same analysis. Clinical outcomes studies demonstrate that gFOBT, FS, and colonoscopy are all effective in reducing CRC-related mortality. Network meta-analysis suggests that colonoscopy is the most effective test. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.
Rossi, Edoardo; Kant, Michael A.; von Rohr, Philipp Rudolf; Saar, Martin O.
2017-04-01
The exploitation of deep geothermal resources for energy production relies on finding cost effective solutions to increase the drilling performance in hard rocks. Conventional rotary drilling techniques, based on mechanical rock exportation, result in high rates of drilling tool wearing, causing significant costs. Additionally, rotary drilling results in low drilling speeds in the typically hard crystalline basement rocks targeted for enhanced geothermal energy utilization technologies. Furthermore, even lower overall drilling rates result, when considering tripping times required to exchange worn drill tools. Therefore, alternative drilling techniques, such as hammering, thermal drilling, plasma drilling, and jetting processes are widely investigated in order to provide cost-effective alternatives to conventional drilling methods. A promising approach, that combines conventional rotary and thermal drilling techniques, is investigated in the present work. Here, the rock material is thermally weakened before being exported by conventional cutters. Heat is locally provided by a flame, which moves over the rock surface, heat-treating the material. Besides reducing the rock strength, an in-depth smoothening effect of the mechanical rock properties is observed due to the thermal treatment. This results in reduced rates of drill bit wearing and higher rates of penetration, which in turn decreases drilling costs significantly, particularly for deep-drilling projects. Due to the high heating rates, rock-hardening, commonly observed at moderate temperatures, can be avoided. The flame action can be modelled as a localized, high heat transfer coefficient flame treatment, which results in orders of magnitude higher heating rates than conventional oven treatments. Therefore, we analyse rock strength variations after different maximum temperatures, flame-based heating rates, and rock confinement pressures. The results show that flame treatments lead to a monotonous decrease of
Monsees, G.; Scherpen, J.M.A.
2001-01-01
This paper presents a novel output-based, discrete-time, sliding mode controller design methodology. In order to reproduce an output target profile, feed-forward controllers yield an excellent performance, however their robustness against disturbances and parameter variations is limited. In this pap
A High-Order Test for Optimality of Bang-Bang Controls.
1983-11-01
Systems * Istituto di Matematica Applicata, Universitl di Padova, ITALY. sponsored by the United States Army under Contract No. DAAG29-80-C-0041...the first order variation at the terminal point of the trajectory lim [x(T,u ) - x(TW)]/E (1.1) Istituto di Matematica Applicata, Universitl di Padova
2010-07-01
... without Chemical Abstracts Service Registry Numbers. 799.5025 Section 799.5025 Protection of Environment... orders for mixtures without Chemical Abstracts Service Registry Numbers. This section sets forth a list of mixtures (with no Chemical Abstracts Service Registry Numbers) which are the subject of...
The Effects of Test Characteristics on the Hierarchical Order of Reading Skills
Badrasawi, Kamal J. I.; Abu Kassim, Noor Lide; Daud, Nuraihan Mat
2017-01-01
Purpose: The study sought to determine the hierarchical nature of reading skills. Whether reading is a "unitary" or "multi-divisible" skill is still a contentious issue. So is the hierarchical order of reading skills. Determining the hierarchy of reading skills is challenging as item difficulty is greatly influenced by factors…
Model Order Selection for Short Data: An Exponential Fitting Test (EFT
Martin Haardt
2007-01-01
Full Text Available High-resolution methods for estimating signal processing parameters such as bearing angles in array processing or frequencies in spectral analysis may be hampered by the model order if poorly selected. As classical model order selection methods fail when the number of snapshots available is small, this paper proposes a method for noncoherent sources, which continues to work under such conditions, while maintaining low computational complexity. For white Gaussian noise and short data we show that the profile of the ordered noise eigenvalues is seen to approximately fit an exponential law. This fact is used to provide a recursive algorithm which detects a mismatch between the observed eigenvalue profile and the theoretical noise-only eigenvalue profile, as such a mismatch indicates the presence of a source. Moreover this proposed method allows the probability of false alarm to be controlled and predefined, which is a crucial point for systems such as RADARs. Results of simulations are provided in order to show the capabilities of the algorithm.
Day, S D; Wong, F M G; Gordon, S R; Wong, L L; Rebak, R B
2003-09-07
Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the Yucca Mountain waste package program has been the integrity of container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal to determine their relative corrosion behavior in SCW at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the electrochemical behavior in the three tested solutions.
Test sequencing problem arising at the design stage for reducing life cycle cost
Zhang Shigang; Hu Zheng; Wen Xisen
2013-01-01
Previous test sequencing algorithms only consider the execution cost of a test at the application stage.Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the execution cost,the sequential diagnosis strategy obtained by previous methods is actually not optimal from the view of life cycle.In this paper,the test sequencing problem based on life cycle cost is presented.It is formulated as an optimization problem,which is non-deterministic polynomial-time hard (NP-hard).An algorithm and a strategy to improve its computational efficiency are proposed.The formulation and algorithms are tested on various simulated systems and comparisons are made with the extant test sequencing methods.Application on a pump rotational speed control (PRSC) system of a spacecraft is studied in detail.Both the simulation results and the real-world case application results suggest that the solution proposed in this paper can significantly reduce the life cycle cost of a sequential fault diagnosis strategy.
Herziger, Atar; Benzerga, Amel; Berkessel, Jana; Dinartika, Niken L; Franklin, Matija; Steinnes, Kamilla K; Sundström, Felicia
2017-01-01
Excessive consumption is on the rise, as is apparent in growing financial debt and global greenhouse gas emissions. Voluntary simplicity, a lifestyle choice of reduced consumption and sustainable consumer behavior, provides a potential solution for excessive consumers. However, voluntary simplicity is unpopular, difficult to adopt, and under researched. The outlined research project will test a method of promoting voluntary simplicity via user-generated content, thus mimicking an existing social media trend (Minimalism) in an empirical research design. The project will test (a) whether the Minimalism trend could benefit consumers interested in reducing their consumption, and (b) whether self-transcendence (i.e., biospheric) and self-enhancement (i.e., egoistic and hedonic) values and goals have a similar impact in promoting voluntary simplicity. A one-week intervention program will test the efficacy of watching user-generated voluntary simplicity videos in reducing non-essential consumption. Each of the two intervention conditions will present participants with similar tutorial videos on consumption reduction (e.g., decluttering, donating), while priming the relevant values and goals (self-transcendence or self-enhancement). These interventions will be compared to a control condition, involving no user-generated content. Participants will undergo baseline and post-intervention evaluations of: voluntary simplicity attitudes and behaviors, buying and shopping behaviors, values and goals in reducing consumption, and life satisfaction. Experience sampling will monitor affective state during the intervention. We provide a detailed stepwise procedure, materials, and equipment necessary for executing this intervention. The outlined research design is expected to contribute to the limited literature on voluntary simplicity, online behavioral change interventions, and the use of social marketing principles in consumer interventions.
Atar Herziger
2017-06-01
Full Text Available Excessive consumption is on the rise, as is apparent in growing financial debt and global greenhouse gas emissions. Voluntary simplicity, a lifestyle choice of reduced consumption and sustainable consumer behavior, provides a potential solution for excessive consumers. However, voluntary simplicity is unpopular, difficult to adopt, and under researched. The outlined research project will test a method of promoting voluntary simplicity via user-generated content, thus mimicking an existing social media trend (Minimalism in an empirical research design. The project will test (a whether the Minimalism trend could benefit consumers interested in reducing their consumption, and (b whether self-transcendence (i.e., biospheric and self-enhancement (i.e., egoistic and hedonic values and goals have a similar impact in promoting voluntary simplicity. A one-week intervention program will test the efficacy of watching user-generated voluntary simplicity videos in reducing non-essential consumption. Each of the two intervention conditions will present participants with similar tutorial videos on consumption reduction (e.g., decluttering, donating, while priming the relevant values and goals (self-transcendence or self-enhancement. These interventions will be compared to a control condition, involving no user-generated content. Participants will undergo baseline and post-intervention evaluations of: voluntary simplicity attitudes and behaviors, buying and shopping behaviors, values and goals in reducing consumption, and life satisfaction. Experience sampling will monitor affective state during the intervention. We provide a detailed stepwise procedure, materials, and equipment necessary for executing this intervention. The outlined research design is expected to contribute to the limited literature on voluntary simplicity, online behavioral change interventions, and the use of social marketing principles in consumer interventions.
Higher order test of Lorentz invariance with an optical ring cavity
Michimura, Yuta; Mewes, Matthew; Matsumoto, Nobuyuki; Ohmae, Noriaki; Kokuyama, Wataru; Aso, Yoichi; Ando, Masaki
2016-01-01
We have developed an apparatus to search for the higher-order Lorentz violation in photons by measuring the resonant frequency difference between two counterpropagating directions of an asymmetric optical ring cavity. From the year-long data taken between 2012 and 2013, we found no evidence for the light speed anisotropy at the level of $\\delta c/c \\lesssim 10^{-15}$. Limits on the dipole components of the anisotropy are improved by more than an order of magnitude, and limits on the hexapole components are obtained for the first time. An overview of our apparatus and the data analysis in the framework of the spherical harmonics decomposition of anisotropy are presented. We also present the status of the recent upgrade of the apparatus.
The rate of invasive testing for trisomy 21 is reduced after implementation of NIPT.
Bjerregaard, Louise; Stenbakken, Anne Betsagoo; Andersen, Camilla Skov; Kristensen, Line; Jensen, Cecilie Vibeke; Skovbo, Peter; Sørensen, Anne Nødgaard
2017-04-01
The non-invasive prenatal test (NIPT) was introduced in the North Denmark Region in March 2013. NIPT is offered as an alternative to invasive tests if the combined first trimester risk of trisomy 21 (T21) is ≥ 1:300. The purpose of this study was to investigate the effect of NIPT implementation among high-risk pregnancies in a region with existing first-trimester combined screening for T21. The primary objective was to examine the effect on the invasive testing rate. This was a retrospective observational study including high-risk singleton pregnancies in the North Denmark Region. The women were included in two periods, i.e. before and after the implementation of NIPT, respectively. Group 1 (before NIPT): n = 253 and Group 2 (after NIPT): n = 302. After NIPT implementation, the invasive testing rate fell from 70% to 48% (p < 0.01), and the number of high-risk women refusing further testing dropped from 26% to 3% (p < 0.01). NIPT successfully detected four cases of T21; however, two out of three sex-chromosomal abnormalities were false positives. No false negative NIPT results were revealed in this study. In the North Denmark Region, the implementation of NIPT in high-risk pregnancies significantly reduced the rate of invasive testing. However, the proportion of high-risk women who opted for prenatal tests increased as the majority of women who previously refused further testing now opted for the NIPT. none. The study was approved by the Danish Data Protection Agency (No. 2015-104). Articles published in the Danish Medical Journal are “open access”. This means that the articles are distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits any non-commercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Tekes, A; Jackson, E M; Ogborn, J; Liang, S; Bledsoe, M; Durand, D J; Jallo, G; Huisman, T A G M
2016-06-01
Lean Six Sigma methodology is increasingly used to drive improvement in patient safety, quality of care, and cost-effectiveness throughout the US health care delivery system. To demonstrate our value as specialists, radiologists can combine lean methodologies along with imaging expertise to optimize imaging elements-of-care pathways. In this article, we describe a Lean Six Sigma project with the goal of reducing the relative use of pediatric head CTs in our population of patients with hydrocephalus by 50% within 6 months. We applied a Lean Six Sigma methodology using a multidisciplinary team at a quaternary care academic children's center. The existing baseline imaging practice for hydrocephalus was outlined in a Kaizen session, and potential interventions were discussed. An improved radiation-free workflow with ultrafast MR imaging was created. Baseline data were collected for 3 months by using the departmental radiology information system. Data collection continued postintervention and during the control phase (each for 3 months). The percentage of neuroimaging per technique (head CT, head ultrasound, ultrafast brain MR imaging, and routine brain MR imaging) was recorded during each phase. The improved workflow resulted in a 75% relative reduction in the percentage of hydrocephalus imaging performed by CT between the pre- and postintervention/control phases (Z-test, P = .0001). Our lean interventions in the pediatric hydrocephalus care pathway resulted in a significant reduction in head CT orders and increased use of ultrafast brain MR imaging. © 2016 by American Journal of Neuroradiology.
Chappell, Mark; Potter, Zach; Hine, Trevor J; Mullen, Kathy T; Shand, James
2013-08-28
Spatial projection and temporal integration are two prominent theories of visual localization for moving stimuli which gain most of their explanatory power from a single process. Spatial projection theories posit that a moving stimulus' perceived position is projected forwards in order to compensate for processing delays (Eagleman & Sejnowski, 2007; Nijhawan, 2008). Temporal integration theories (Krekelberg & Lappe, 2000) suggest that an averaging over positions occupied by the moving stimulus for a period of time is the dominant process underlying perception of position. We found that when magnocellular (M) pathway processing was reduced, there were opposite effects on localization judgments when a smooth, continuous trajectory was used, compared to when the moving object suddenly appeared, or suddenly reversed direction. The flash-lag illusion was decreased for the continuous trajectory, but increased for the onset and reversal trajectories. This cross-over interaction necessitates processes additional to those proposed by either the spatial projection or temporal integration theories in order to explain the perception of the position of moving stimuli across all our conditions. Differentiating our onset trajectory conditions from a Fröhlich illusion, in a second experiment, we found a null Fröhlich illusion under normal luminance-defined conditions, significantly smaller than the corresponding flash-lag illusion, but significantly increased when M processing was reduced. Our data are most readily accounted for by Kirschfeld and Kammer's (1999) backward-inhibition and focal attention theory.
Survival of the ’net’est? Experiences with electronic test tools – reduced teacher hours?
Kristin Dale
2008-07-01
Full Text Available More feedback to students is demanded to improve educational quality. In large courses individual feedback is often very time-demanding for the teacher. If teacher hours are only marginally increased to cover increased student feedback, teachers should look for electronic tools for assistance with student feedback that will reduce teacher work hours, at least in the long run. This paper reports my experiences with electronic multiple – choice tests in mid-term feed-back to students in large courses in undergraduate studies. It reports a lot of the decisions that the teacher has to make when creating a multiple-choice test for a course such as the choice between a paper or electronic test, number and type of questions, number of answer options, scores for right and wrong answers and manual or electronic scoring. The paper also addresses the communication with students before and after the test, the need for administrative support and finally discusses the costs and benefits with respect to teacher hours. These experiences may be useful to teachers who consider using electronic test-tools.
Lee, Kyo-Beum; Blaabjerg, Frede
2004-01-01
This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new...... matrix converter model. Regulated Order Extended Luenberger Observer (ROELO) is employed to bring better response in the whole speed operation range and a method to select the observer gain is presented. Experimental results are shown to illustrate the performance of the proposed system...
2011-07-15
... COMMISSION Order Approving Adjustment for Inflation of the Dollar Amount Tests in Rule 205-3 Under the... dollar amount thresholds to account for the effects of inflation in 1998.\\3\\ \\3\\ See Exemption To Allow... and every five years thereafter, the Commission shall adjust for inflation the dollar...
Macek, M
2014-01-01
We present a comprehensive analysis of the emerging order and chaos and enduring symmetries, accompanying a generic (high-barrier) first-order quantum phase transition (QPT). The interacting boson model Hamiltonian employed, describes a QPT between spherical and deformed shapes, associated with its U(5) and SU(3) dynamical symmetry limits. A~classical analysis of the intrinsic dynamics reveals a rich but simply-divided phase space structure with a H\\'enon-Heiles type of chaotic dynamics ascribed to the spherical minimum and a robustly regular dynamics ascribed to the deformed minimum. The simple pattern of mixed but well-separated dynamics persists in the coexistence region and traces the crossing of the two minima in the Landau potential. A quantum analysis discloses a number of regular low-energy U(5)-like multiplets in the spherical region, and regular SU(3)-like rotational bands extending to high energies and angular momenta, in the deformed region. These two kinds of regular subsets of states retain thei...
Macek, M., E-mail: mmacek@Racah.phys.huji.ac.il; Leviatan, A., E-mail: ami@phys.huji.ac.il
2014-12-15
We present a comprehensive analysis of the emerging order and chaos and enduring symmetries, accompanying a generic (high-barrier) first-order quantum phase transition (QPT). The interacting boson model Hamiltonian employed, describes a QPT between spherical and deformed shapes, associated with its U(5) and SU(3) dynamical symmetry limits. A classical analysis of the intrinsic dynamics reveals a rich but simply-divided phase space structure with a Hénon–Heiles type of chaotic dynamics ascribed to the spherical minimum and a robustly regular dynamics ascribed to the deformed minimum. The simple pattern of mixed but well-separated dynamics persists in the coexistence region and traces the crossing of the two minima in the Landau potential. A quantum analysis discloses a number of regular low-energy U(5)-like multiplets in the spherical region, and regular SU(3)-like rotational bands extending to high energies and angular momenta, in the deformed region. These two kinds of regular subsets of states retain their identity amidst a complicated environment of other states and both occur in the coexistence region. A symmetry analysis of their wave functions shows that they are associated with partial U(5) dynamical symmetry (PDS) and SU(3) quasi-dynamical symmetry (QDS), respectively. The pattern of mixed but well-separated dynamics and the PDS or QDS characterization of the remaining regularity, appear to be robust throughout the QPT. Effects of kinetic collective rotational terms, which may disrupt this simple pattern, are considered.
E. A. Bondar
2010-06-01
Full Text Available It is shown that at present an acceptable way of reducing the concentration of harmful substances in the surface layer of the atmosphere at rheostat tests of locomotives is their dispersion in a large volume of air. Channels, installed above an exhaust pipe of diesel locomotive with a break at the gas flow, work as ejectors. We have solved jointly the equation of aerodynamic characteristics of the ejector device and the equation of diffusion of gases; as a result the calculated dependence for determining the necessary height of ejector device has been obtained.
A NEW TEST PROCEDURE FOR NEW BETTER THAN USED IN INCREASING CONVEX ORDERING
LI Xiaohu
2004-01-01
A new nonparametric procedure is developed to test the exponentiality against the strict NBUC property of a life distribution. The exact null distribution is derived by the theory of sample spacings, and the asymptotic normality is also established by the large sample theory of L-statistics. Finally, the lower and upper tailed probability of the exact null distribution and some numerical simulation results are presented as well.
Design and Analysis of Reduced Test Power in Scan Based Design
G.Sowmiya
2013-04-01
Full Text Available Low power VLSI testing is indispensible in switching components and number of hardware/software-based techniques has been still developed to minimize the dynamic power dissipation. In earlier days, primary concerns of VLSI design were focused in area, performance, cost and reliability. But in current years, the design constraints have begun to change because of increasing low power testing. XOR network based techniques have been widely implemented for large scan chain design owing to its high compression ratio. The proposed work explores the reduction of scan power by reducing the number of switching in the XOR network. This work is also associated with Travelling Salesman problem to find out the least number of switching.
Reduced activation martensitic steels as a structural material for ITER test blanket
Shiba, K. E-mail: shiba@realab01.tokai.jaeri.go.jp; Enoeda, M.; Jitsukawa, S
2004-08-01
A Japanese ITER test blanket module (TBM) is planed to use reduced-activation martensitic steel F82H. Feasibility of F82H for ITER test blanket module is discussed in this paper. Several kinds of property data, including physical properties, magnetic properties, mechanical properties and neutron-irradiation data on F82H have been obtained, and these data are complied into a database to be used for the designing of the ITER TBM. Currently obtained data suggests F82H will not have serious problems for ITER TBM. Optimization of F82H improves the induced activity, toughness and HIP resistance. Furthermore, modified F82H is resistant to temperature instability during material production.
Hjortø, Line; Ettema, Jehan Frans; Kargo, Morten
2015-01-01
, especially if genomic tests are used in combination with sexed semen or a high management level for reproductive performance, because both factors provide the opportunity for generating a reproductive surplus in the herd. In this study, sexed semen is used in combination with beef semen to produce high-value...... simulates the parity distribution of the dams of heifer calves. The ADAM program estimates genetic merit per year in a herd under different strategies for use of sexed semen and genomic tests. The annual net return per slot was calculated as the sum of operational return and value of genetic lag minus costs......Until now, genomic information has mainly been used to improve the accuracy of genomic breeding values for breeding animals at a population level. However, we hypothesize that the use of information from genotyped females also opens up the possibility of reducing genetic lag in a dairy herd...
Mottaghi, S.; Benaroya, H.
2016-11-01
A first-principles variational approach is proposed for reduced-order modeling of fluid-structure interaction (FSI) systems, specifically vortex-induced vibration (VIV). FSI has to be taken into account in the design and analysis of many engineering applications, yet a comprehensive theoretical development where analytical equations are derived from first principles is nonexistent. An approach where Jourdain's principle is modified and extended for FSI is used to derive reduced-order models from an extended variational formulation where assumptions are explicitly stated. Two VIV models are considered: an elastically supported, inverted pendulum and a translating cylinder, both immersed in a flow and allowed to move transversely to the flow direction. Their reduced-order models are obtained in the form of (i) a single governing equation and (ii) two general coupled equations as well as the coupled lift-oscillator model. Comparisons are made with three existing models. Based on our theoretical results, and especially the reduced-order model, we conclude that the first principles development herein is a viable framework for the modeling of complex fluid-structure interaction problems such as vortex-induced oscillations.
Pǎcurar, Cristina; Hepuť, Teodor; Ardelean, Marius
2016-06-01
As the basic units in the preparation of steel, in industrial practice is used oxygen converters and electric arc furnaces. In research carried out has been taken into account structure analysis load electric arc furnaces of the specific consumption of electricity (kWh/t). Data to be achieved for a number of 96 batches, have been taken into account load holding metal of each assortment of scrap metal, these varieties being considered as independent parameters, and electricity consumption is considered dependent parameter. By processing the data in the EXCEL spreadsheet programs and MATLAB have been obtained correlations between parameters analyze, analytical results being presented and the graph. On the basis of an analysis of these correlations to choose optimal structure of the load in order to obtain an acceptable energy consumption from technical and economic point of view.
A strategy to reduce the numbers of fish used in acute ecotoxicity testing of pharmaceuticals.
Hutchinson, Thomas H; Barrett, Sarah; Buzby, Mary; Constable, David; Hartmann, Andreas; Hayes, Eileen; Huggett, Duane; Laenge, Reinhard; Lillicrap, Adam D; Straub, Jürg Oliver; Thompson, Roy S
2003-12-01
The pharmaceutical industry gives high priority to animal welfare in the process of drug discovery and safety assessment. In the context of environmental assessments of active pharmaceutical ingredients (APIs), existing U.S. Food and Drug Administration and draft European regulations may require testing of APIs for acute ecotoxicity to algae, daphnids, and fish (base-set ecotoxicity data used to derive the predicted no-effect concentration [PNECwater] from the most sensitive of three species). Subject to regulatory approval, it is proposed that testing can be moved from fish median lethal concentration (LC50) testing (typically using > or = 42 fish/API) to acute threshold tests using fewer fish (typically 10 fish/API). To support this strategy, we have collated base-set ecotoxicity data from regulatory studies of 91 APIs (names coded for commercial reasons). For 73 of the 91 APIs, the algal median effect concentration (EC50) and daphnid EC50 values were lower than or equal to the fish LC50 data. Thus, for approximately 80% of these APIs, algal and daphnid acute EC50 data could have been used in the absence of fish LC50 data to derive PNECwater values. For the other 18 APIs, use of an acute threshold test with a step-down factor of 3.2 is predicted to give comparable PNECwater outcomes. Based on this preliminary scenario of 91 APIs, this approach is predicted to reduce the total number of fish used from 3,822 to 1,025 (approximately 73%). The present study, although preliminary, suggests that the current regulatory requirement for fish LC50 data regarding APIs should be succeeded by fish acute threshold (step-down) test data, thereby achieving significant animal welfare benefits with no loss of data for PNECwater estimates.
Levi Bolin, B; Alcorn, Joseph L; Lile, Joshua A; Rush, Craig R; Rayapati, Abner O; Hays, Lon R; Stoops, William W
2017-09-01
Disrupted glutamate homeostasis is thought to contribute to cocaine-use disorder, in particular, by enhancing the incentive salience of cocaine stimuli. n-Acetylcysteine might be useful in cocaine-use disorder by normalizing glutamate function. In prior studies, n-acetylcysteine blocked the reinstatement of cocaine seeking in laboratory animals and reduced the salience of cocaine stimuli and delayed relapse in humans. The present study determined the ability of maintenance on n-acetylcysteine (0 or 2400mg/day, counterbalanced) to reduce the incentive salience of cocaine stimuli, as measured by an attentional bias task, and attenuate intranasal cocaine self-administration (0, 30, and 60mg). Fourteen individuals (N=14) who met criteria for cocaine abuse or dependence completed this within-subjects, double-blind, crossover-design study. Cocaine-cue attentional bias was greatest following administration of 0mg cocaine during placebo maintenance, and was attenuated by n-acetylcysteine. Cocaine maintained responding during placebo and n-acetylcysteine maintenance, but the reinforcing effects of cocaine were significantly attenuated across both maintenance conditions in participants maintained on n-acetylcysteine first compared to participants maintained on placebo first. These results collectively suggest that a reduction in the incentive salience of cocaine-related stimuli during n-acetylcysteine maintenance may be accompanied by reductions in cocaine self-administration. These results are in agreement with, and link, prior preclinical and clinical trial results suggesting that n-acetylcysteine might be useful for preventing cocaine relapse by attenuating the incentive salience of cocaine cues. Copyright © 2017 Elsevier B.V. All rights reserved.
Haahr, Thor; Ersbøll, Anne S; Karlsen, Mona A; Svare, Jens; Sneider, Kirstine; Hee, Lene; Weile, Louise K; Ziobrowska-Bech, Agnes; Østergaard, Claus; Jensen, Jørgen S; Helmig, Rikke B; Uldbjerg, Niels
2016-08-01
Bacterial vaginosis (BV) is characterized by a dysbiosis of the vaginal microbiota with a depletion of Lactobacillus spp. In pregnancy, prevalence's between 7 and 30% have been reported depending on the study population and the definition. BV may be associated with an increased risk of spontaneous preterm delivery (sPTD). However, it is controversial whether or not BV-positive pregnant women will benefit from treatment to reduce the risk of sPTD. We could not identify any good-quality guideline addressing this issue. Consequently we aimed to produce this clinical recommendation based on GRADE. Systematic literature searches were conducted in the following databases: Guidelines International Network: G-I-N, Medline, Embase, The Cochrane Database of Systematic Reviews, Web of Science and http://www.clinicaltrials.gov from 1999 to 3 October 2014. Hence, nine guidelines, 34 reviews, 18 randomized controlled trials and 12 observational studies were included. The GRADE quality of evidence was consistently low or very low, primarily because none of the risk ratios (RR) for the risk of sPTD at treatment with metronidazole, RR was 1.11 (95% CI 0.93-1.34) in low-risk pregnancies and 0.96 (95% CI 0.78-1.18) in high risk pregnancies. Concerning treatment with clindamycin at any gestational age, the RR was 0.87 (95% CI 0.73-1.05). This systematic review gives a strong recommendation against treatment with metronidazole and a weak recommendation against treatment with clindamycin to reduce the sPTD rate in both high-risk and low-risk pregnancies with BV. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.
Renaud, Guillaume; Talmant, Maryline; Marrelec, Guillaume
2016-01-01
International audience; The nonlinear elasticity of solids at the microstrain level has been recently studied by applying dynamic acousto-elastic testing. It is the analog of conventional quasi-static acousto-elastic experiments but the strain-dependence (or stress-dependence) of ultrasonic wave-speed is measured with an applied strain ranging from 10−7 to 10−5 and produced by a stationary elastic wave. In conventional quasi-static acousto-elastic experiments, the strain is applied in a quasi...
Johannes Hessler
Full Text Available A phase of mild cognitive impairment (MCI precedes most forms of neurodegenerative dementia. Many definitions of MCI recommend the use of test norms to diagnose cognitive impairment. It is, however, unclear whether the use of norms actually improves the detection of individuals at risk of dementia. Therefore, the effects of age- and education-norms on the validity of test scores in predicting progression to dementia were investigated.Baseline cognitive test scores (Syndrome Short Test of dementia-free participants aged ≥65 were used to predict progression to dementia within three years. Participants were comprehensively examined one, two, and three years after baseline. Test scores were calculated with correction for (1 age and education, (2 education only, (3 age only and (4 without correction. Predictive validity was estimated with Cox proportional hazard regressions. Areas under the curve (AUCs were calculated for the one-, two-, and three-year intervals.82 (15.3% of initially 537 participants, developed dementia. Model coefficients, hazard ratios, and AUCs of all scores were significant (p<0.001. Predictive validity was the lowest with age-corrected scores (-2 log likelihood = 840.90, model fit χ2 (1 = 144.27, HR = 1.33, AUCs between 0.73 and 0.87 and the highest with education-corrected scores (-2 log likelihood = 815.80, model fit χ2 (1 = 171.16, HR = 1.34, AUCs between 0.85 and 0.88.The predictive validity of test scores is markedly reduced by age-correction. Therefore, definitions of MCI should not recommend the use of age-norms in order to improve the detection of individuals at risk of dementia.
Spiegel, L.; Kerkau, M.; Bofinger, G.; Mueller, S.; Meier, R.; Neusser, H.J. [Dr. Ing. h.c. F. Porsche AG, Weissach (Germany)
2008-07-01
In current sports car development - where fuel efficiency has always played a predominant role - one of the central targets is the reduction of fuel consumption. In order to maximize the benefits of improved fuel economy it is necessary to consistently optimize many of the known parameters and have them controlled by a corresponding Powertrain Management System. This presentation explains Porsche's layout philosophy and outlines the technologies used to implement a Powertrain Management specifically designed for application in sports cars. This Powertrain Management System coordinates the chosen technologies and combines them into an efficient drive system. The driver is given the possibility of making his choice between a regular program and a sports option. Further, this presentation describes a Thermal Management System meant to optimize engine warm-up as well as the part-load and full-load modes while giving consideration to the specific requirements of sports car operation. It also deals in great detail with the inherent potential of an idle stop system and its integration into the car, which is rather complicated. In addition, this paper looks into adaptive shift strategies for automatic transmissions with the aim of automatically selecting performance-oriented shift points tuned for optimum fuel consumption values. (orig.)
Kannan, Govind; Milani, Ali A; Panahi, Issa M S; Briggs, Richard W
2011-12-01
Functional magnetic resonance imaging (fMRI) acoustic noise exhibits an almost periodic nature (quasi-periodicity) due to the repetitive nature of currents in the gradient coils. Small changes occur in the waveform in consecutive periods due to the background noise and slow drifts in the electroacoustic transfer functions that map the gradient coil waveforms to the measured acoustic waveforms. The period depends on the number of slices per second, when echo planar imaging (EPI) sequencing is used. Linear predictability of fMRI acoustic noise has a direct effect on the performance of active noise control (ANC) systems targeted to cancel the acoustic noise. It is shown that by incorporating some samples from the previous period, very high linear prediction accuracy can be reached with a very low order predictor. This has direct implications on feedback ANC systems since their performance is governed by the predictability of the acoustic noise to be cancelled. The low complexity linear prediction of fMRI acoustic noise developed in this paper is used to derive an effective and low-cost feedback ANC system.
Habibollah Mohamadi
2014-08-01
Full Text Available Recently, much attention has been given to Stochastic demand due to uncertainty in the real -world. In the literature, decision-making models and suppliers' selection do not often consider inventory management as part of shopping problems. On the other hand, the environmental sustainability of a supply chain depends on the shopping strategy of the supply chain members. The supplier selection plays an important role in the green chain. In this paper, a multi-objective nonlinear integer programming model for selecting a set of supplier considering Stochastic demand is proposed. while the cost of purchasing include the total cost, holding and stock out costs, rejected units, units have been delivered sooner, and total green house gas emissions are minimized, while the obtained total score from the supplier assessment process is maximized. It is assumed, the purchaser provides the different products from the number predetermined supplier to a with Stochastic demand and the uniform probability distribution function. The product price depends on the order quantity for each product line is intended. Multi-objective models using known methods, such as Lp-metric has become an objective function and then uses genetic algorithms and simulated annealing meta-heuristic is solved.
Costigan, K.R.
1998-11-01
Deseret Chemical Depot is one of the US Army`s storage facilities for its stockpile of chemical weapon agents. Congress has directed the Department of Defense to eliminate the aging stockpiles, which have existed since the end of World War II, and the US Army is destroying these lethal chemical munitions. Although the danger is slight, accurate predictions of the wind field in the valley are necessary for dispersion calculations in the event of an accident involving toxic chemicals at the depot. There are several small communities in Rush and Tooele valleys, including the town of Tooele, and Salt Lake City is located 65 km to the Northeast of Deseret Chemical Depot South area, at 1,300 m MSL and beyond the Oquirrh Mountains. The purpose of this report is to carry out three-dimensional numerical simulations of the atmospheric circulations in the region around Deseret Chemical Depot with the Higher Order Turbulence Model for Atmospheric Circulations (HOTMAC) and to evaluate the performance of the model. The code had been modified to assimilate local meteorological observations through the use of Newtonian nudging. The nudging scheme takes advantage of the extensive network of local observations in the valley.
A test of macromolecular crystallization in microgravity: large well ordered insulin crystals.
Borgstahl, G E; Vahedi-Faridi, A; Lovelace, J; Bellamy, H D; Snell, E H
2001-08-01
Crystals of insulin grown in microgravity on Space Shuttle Mission STS-95 were extremely well ordered and unusually large (many >2 mm). The physical characteristics of six microgravity and six earth-grown crystals were examined by X-ray analysis employing superfine phi slicing and unfocused synchrotron radiation. This experimental setup allowed hundreds of reflections to be precisely examined from each crystal in a short period of time. The microgravity crystals were on average 34 times larger, had sevenfold lower mosaicity, had 54-fold higher reflection peak heights and diffracted to significantly higher resolution than their earth-grown counterparts. A single mosaic domain model could account for the observed reflection profiles in microgravity crystals, whereas data from earth crystals required a model with multiple mosaic domains. This statistically significant and unbiased characterization indicates that the microgravity environment was useful for the improvement of crystal growth and the resultant diffraction quality in insulin crystals and may be similarly useful for macromolecular crystals in general.
Astrophysical Tests of Kinematical Conformal Cosmology in Fourth-Order Conformal Weyl Gravity
Gabriele U. Varieschi
2014-12-01
Full Text Available In this work we analyze kinematical conformal cosmology (KCC, an alternative cosmological model based on conformal Weyl gravity (CG, and test it against current type Ia supernova (SNIa luminosity data and other astrophysical observations. Expanding upon previous work on the subject, we revise the analysis of SNIa data, confirming that KCC can explain the evidence for an accelerating expansion of the Universe without using dark energy or other exotic components. We obtain an independent evaluation of the Hubble constant, H0 = 67:53 kms-1 Mpc-1, very close to the current best estimates. The main KCC and CG parameters are re-evaluated and their revised values are found to be close to previous estimates. We also show that available data for the Hubble parameter as a function of redshift can be fitted using KCC and that this model does not suffer from any apparent age problem. Overall,
Marsh, Herbert W; Trautwein, Ulrich; Lüdtke, Oliver; Köller, Olaf; Baumert, Jürgen
2005-01-01
Reciprocal effects models of longitudinal data show that academic self-concept is both a cause and an effect of achievement. In this study this model was extended to juxtapose self-concept with academic interest. Based on longitudinal data from 2 nationally representative samples of German 7th-grade students (Study 1: N = 5,649, M age = 13.4; Study 2: N = 2,264, M age = 13.7 years), prior self-concept significantly affected subsequent math interest, school grades, and standardized test scores, whereas prior math interest had only a small effect on subsequent math self-concept. Despite stereotypic gender differences in means, linkages relating these constructs were invariant over gender. These results demonstrate the positive effects of academic self-concept on a variety of academic outcomes and integrate self-concept with the developmental motivation literature.
Cantu, David C.; Malhotra, Deepika; Koech, Phillip K.; Heldebrant, David J.; Zheng, Feng (Richard); Freeman, Charles J.; Rousseau, Roger; Glezakou, Vassiliki-Alexandra
2016-01-01
CO2 capture from power generation with aqueous solvents remains energy intensive due to the high water content of the current technology, or the high viscosity of non-aqueous alternatives. Quantitative reduced models, connecting molecular structure to bulk properties, are key for developing structure-property relationships that enable molecular design. In this work, we describe such a model that quantitatively predicts viscosities of CO2 binding organic liquids (CO2BOLs) based solely on molecular structure and the amount of bound CO2. The functional form of the model correlates the viscosity with the CO2 loading and an electrostatic term describing the charge distribution between the CO2-bearing functional group and the proton-receiving amine. Molecular simulations identify the proton shuttle between these groups within the same molecule to be the critical indicator of low viscosity. The model, developed to allow for quick screening of solvent libraries, paves the way towards the rational design of low viscosity non-aqueous solvent systems for post-combustion CO2 capture. Following these theoretical recommendations, synthetic efforts of promising candidates and viscosity measurement provide experimental validation and verification.
Aida Rodríguez, Sara; Alcalá, Jorge; Martins Souza, Roberto
2011-03-01
of correction with the ratio E/Ei . The most affected parameter in the indentation curve, as a consequence of the indentation deformation, was the ratio between the residual indentation depth after complete unloading and the maximum indenter displacement, δr/δmax (up to 26%), but this variation did not significantly decrease the capability to estimate hardness and elastic modulus based on the ratio of the residual indentation depth to maximum indentation depth, hr/hmax . In general, the results confirm the convenience of the use of the reduced modulus in the spherical instrumented indentation tests.
S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak
2006-05-08
Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.
Performance and durability tests of smart icephobic coatings to reduce ice adhesion
Janjua, Zaid A.; Turnbull, Barbara; Choy, Kwang-Leong; Pandis, Christos; Liu, Junpeng; Hou, Xianghui; Choi, Kwing-So
2017-06-01
The accretion of ice can cause damage in applications ranging from power lines and shipping decks, to wind turbines and rail infrastructure. In particular on aircraft, it can change aerodynamic characteristics, greatly affecting the flight safety. Commercial aircraft are therefore required to be equipped with de-icing devices, such as heating mats over the wings. The application of icephobic coatings near the leading edge of a wing can in theory reduce the high power requirements of heating mats, which melt ice that forms there. Such coatings are effective in preventing the accretion of runback ice, formed from airborne supercooled droplets, or the water that the heating mats generate as it is sheared back over the wing's upper surface. However, the durability and the practicality of applying them over a large wing surface have been prohibitive factors in deploying this technology so far. Here, we evaluated the ice adhesion strength of four non-conductive coatings and seven thermally conductive coatings by shearing ice samples from coated plates by spinning them in a centrifuge device. The durability of the coating performance was also assessed by repeating the tests, each time regrowing ice samples on the previously-used coatings. Contact angle parameters of each coating were tested for each test to determine influence on ice adhesion strength. The results indicate that contact angle hysteresis is a crucial parameter in determining icephobicity of a coating and hydrophobicity is not necessarily linked to icephobicity.
Goury, Olivier; Amsallem, David; Bordas, Stéphane Pierre Alain; Liu, Wing Kam; Kerfriden, Pierre
2016-08-01
In this paper, we present new reliable model order reduction strategies for computational micromechanics. The difficulties rely mainly upon the high dimensionality of the parameter space represented by any load path applied onto the representative volume element. We take special care of the challenge of selecting an exhaustive snapshot set. This is treated by first using a random sampling of energy dissipating load paths and then in a more advanced way using Bayesian optimization associated with an interlocked division of the parameter space. Results show that we can insure the selection of an exhaustive snapshot set from which a reliable reduced-order model can be built.
TestMeEast: a campaign to increase HIV testing in hospitals and to reduce late diagnosis.
Bath, R; O'Connell, R; Lascar, M; Ferrand, R; Strachan, S; Matin, N; Bassnet, I; Orkin, C
2016-01-01
Late diagnosis occurs in almost half of those diagnosed in the UK (HIV Prevention England, 2013. Retrieved June 22, 2014, from HIV Prevention England: http://www.hivpreventionengland.org.uk/Campaigns-Current/National-HIV-Testing-Week ). Testing occurs mainly in sexual health and antenatal clinics despite recommendations to test more broadly [Ellis, S., & Curtis, H. (2012). HIV diagnoses and missed opportunities. Results of the British HIV association (BHIVA) National Audit 2010. Clinical Medicine, 12(5), 430-434]. We report the findings of an HIV-testing week campaign to offer testing to those who have blood tests as part of routine care within outpatient clinics and emergency departments of six London hospitals. The campaign target was to test 500 patients a day during the 2013 National HIV Testing Week (NHTW). Clinic staff and medical students were trained to offer routine HIV testing. Linkage to care was arranged for those who tested HIV-positive. During NHTW we tested 2402 of the planned 2500 test target. 2402/4317 (55.6% 95% CI 54.1-57.1%) of those who had routine blood tests were tested for HIV. There were eight HIV-positive tests; three were new diagnoses (all linked to care). The campaign hashtag #TestMeEast achieved a total Twitter "reach" of 238, 860 and the campaign had widespread news coverage. Our campaign showed that staff and students could be trained and mobilised to do thousands of routine HIV tests during a campaign.
Theel, Elitza S; Johnson, Ryan D; Plumhoff, Elizabeth; Hanson, Curtis A
2015-04-01
We surveyed national Helicobacter pylori diagnostic testing practices and diagnoses using commercial and Medicare medical claims data from Optum Labs (Cambridge, MA). Serologic testing for antibodies to H. pylori remains the most commonly ordered diagnostic test despite recent expert recommendations. Changes in reimbursement for serologic testing will likely drive future provider ordering practices. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Mary B. Wilson
2015-10-01
Full Text Available This study uses a first-order approximation of a micro-building to investigate the major factors determining how increased thermal capacitance (ITC with thermal storage management (TSM can reduce energy consumption in locations with relatively mild weather conditions such as the southeastern part of the United States of America. In this study, ITC is achieved through water circulation between a large storage tank and pipes embedded within the building envelope. Although ITC results in a larger dominant time constant for the thermal response of a building, an adaptive allocation and control of the added capacitance through TSM significantly improves the benefits of the extra capacitance. This paper compares two first-order models for a micro-building: a reference case model with a single lumped thermal capacitance associated with the building, and another model, with the building’s capacitance plus the capacitance of the water system. Results showed that the ITC/TSM system reduced the cost of conditioning the building by reducing the operating time of both the cooling and the heating systems. May through September, the air conditioning operating time was reduced by an average of 70%, and October through April, the operation of the heating system was reduced by an average of 25%.
Red wine is less stress reducing than vodka; no differences in neuroendocrine challenge test.
Jarrett, N; Peatfield, R; Glover, V
1997-01-01
Red wine, like the drugs reserpine and fenfluramine, causes the release of 5-hydroxytryptamine (5-HT) from storage sites in vitro. This study used a neuroendocrine challenge test design to determine whether the parallel between red wine and these drugs can be extended to central actions in healthy volunteers. Vodka diluted to an equal alcohol content was used as a control. No significant differences were observed between the groups in plasma cortisol, plasma prolactin or in temperature levels. Thus no evidence was obtained for a central 5-HT releasing action by red wine. Self-rating stress and arousal questionnaires were also given. No differences were found in arousal. However whereas vodka had a clear effect in reducing stress, red wine did not. This suggests that red wine does have psychoactive properties independent of its alcohol effects.
Raj, Baldev [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Jayakumar, T., E-mail: tjk@igcar.gov.in [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)
2011-10-01
For the development of Reduced Activation Ferritic-Martensitic Steel (RAFMS), for the Indian Test Blanket Module for ITER, a 3-phase programme has been adopted. The first phase consists of melting and detailed characterization of a laboratory scale heat conforming to Eurofer 97 composition, to demonstrate the capability of the Indian industry for producing fusion grade steel. In the second phase which is currently in progress, the chemical composition will be optimized with respect to tungsten and tantalum for better combination of mechanical properties. Characterization of the optimized commercial scale India-specific RAFM steel will be carried out in the third phase. The first phase of the programme has been successfully completed and the tensile, impact and creep properties are comparable with Eurofer 97. Laser and electron beam welding parameters have been optimized and welding consumables were developed for Narrow Gap - Gas Tungsten Arc welding and for laser-hybrid welding.
Tanigawa, H. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)], E-mail: tanigawa.hiroyasu@jaea.go.jp; Hirose, T.; Shiba, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kasada, R. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Wakai, E. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Serizawa, H.; Kawahito, Y. [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Jitsukawa, S. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kimura, A. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kohno, Y. [Department of Materials Science and Engineering, Muroran Institute of Technology, Muroran, Hokkaido 050-8585 (Japan); Kohyama, A. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Katayama, S. [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Mori, H.; Nishimoto, K. [Division of Materials and Manufacturing Science, Osaka University, Ibaraki, Osaka 565-0871 (Japan); Klueh, R.L.; Sokolov, M.A.; Stoller, R.E.; Zinkle, S.J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6132 (United States)
2008-12-15
Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems. The RAFM F82H was developed in Japan with emphasis on high-temperature properties and weldability. Extensive irradiation studies have conducted on F82H, and it has the most extensive available database of irradiated and unirradiated properties of all RAFMs. The objective of this paper is to review the R and D status of F82H and to identify the key technical issues for the fabrication of an ITER test blanket module (TBM) suggested from the recent research achievements in Japan. This work clarified that the primary issues with F82H involve welding techniques and the mechanical properties of weld joints. This is the result of the distinctive nature of the joint caused by the phase transformation that occurs in the weld joint during cooling, and its impact on the design of a TBM will be discussed.
Harmono Harmono
2017-03-01
Full Text Available This study aimed to test the pecking order theory through its correlation among earnings dimension, capitalstructure, dividend policy and firm’s value perspective. By loading the correlation between dimension one toanother, it indicated that management behavior tended to retained earnings accumulation or to debt collectionin financing the operation of the firm. The pecking order theory were tested when the management behaviortended to retained earnings in accumulating sources of the fund equity rather than borrowing liabilities fromcreditors. Therefore, rationally if the capital structure was optimum, management tended to external financinguntil any trade off between earnings and debt financing. Based on the testing hypothesis, it indicated that therole of capital structure dimension had significance as intervening variable between earnings dimension andfirm’s value. On the other hand, the dividend policy had no significance to become intervening variable.Empirically, it could be concluded that the management behavior in Indonesia tended to leverage rather thanretained earnings accumulation in supporting the pecking order theory. Furthermore, the variable had the roleto differentiate the characteristic of industries represented by the capital structure dimension, especially, debtto assets and debt to equity ratio.
Usability Testing of the BRANCH Smartphone App Designed to Reduce Harmful Drinking in Young Adults.
Milward, Joanna; Deluca, Paolo; Drummond, Colin; Watson, Rod; Dunne, Jacklyn; Kimergård, Andreas
2017-08-08
Electronic screening and brief intervention (eSBI) apps demonstrate potential to reduce harmful drinking. However, low user engagement rates with eSBI reduce overall effectiveness of interventions. As "Digital Natives," young adults have high expectations of app quality. Ensuring that the design, content, and functionality of an eSBI app are acceptable to young adults is an integral stage to the development process. The objective of this study was to identify usability barriers and enablers for an app, BRANCH, targeting harmful drinking in young adults. The BRANCH app contains a drinking diary, alcohol reduction goal setting functions, normative drinking feedback, and information on risks and advice for cutting down. The app includes a social feature personalized to motivate cutting down and to promote engagement with a point-based system for usage. Three focus groups were conducted with 20 users who had tested the app for 1 week. A detailed thematic analysis was undertaken. The first theme, "Functionality" referred to how users wanted an easy-to-use interface, with minimum required user-input. Poor functionality was considered a major usability barrier. The second theme, "Design" described how an aesthetic with minimum text, clearly distinguishable tabs and buttons and appealing infographics was integral to the level of usability. The final theme, "Content" described how participants wanted all aspects of the app to be automatically personalized to them, as well as providing them with opportunities to personalize the app themselves, with increased options for social connectivity. There are high demands for apps such as BRANCH that target skilled technology users including young adults. Key areas to optimize eSBI app development that emerged from testing BRANCH with representative users include high-quality functionality, appealing aesthetics, and improved personalization.
Herron, A. J.; Reed, D. K.; Nance, D. K.
2015-01-01
Characterization of launch vehicle unsteady aerodynamics is a field best studied through experimentation, which is often carried out in the form of large scale wind tunnel testing. Measurement of the fluctuating pressures induced by the boundary layer noise is customarily made with miniature pressure transducers installed into a model of the vehicle of interest. Literature shows that noise level increases between two to five decibels (dB referenced to 20 micropascal) can be induced when the transducer surface is not mounted perfectly flush with the model outer surface. To reduce this artificially induced noise, special transducer holders have been used for aeroacoustic wind tunnel testing by NASA. This holder is a sleeve into which the transducer fits, with a cap that allows it to be mounted in a recessed hole in the model. A single hole in the holder allows the transport of the tunnel medium so the transducer can discriminate the fluctuating pressure due to the turbulent boundary layer noise. The holder is first dry fitted into the model and any difference in height between the holder and the model surface can be sanded flush. The holder is then removed from the model, the transducer glued inside the holder, and the holder replaced in the model, secured also with glue, thus eliminating the problem of noise level increases due to lack of flushness. In order to work with this holder design, special transducers have been ordered with their standard screen removed and the diaphragm moved as close to the top of the casing as possible to minimize any cavity volume. Although this greatly reduces induced noise due to the transducers being out of flush, the holders can also induce a cavity resonance that is usually at a very high frequency. This noise is termed transducer mount induced noise (XMIN). The peak of the mode can vary with the cavity depth, boundary layer noise that can excite the mode, tunnel flow medium, and the build of the transducers. Because the boundary
A clinical trial testing the efficacy of an ionic toothbrush for reducing plaque and gingivitis.
Moreira, Carlos Heitor Cunha; Luz, Patrícia Blaya; Villarinho, Eduardo Aydos; Petri, Luciano Costa; Weidlich, Patrícia; Rösing, Cassiano Kuchenbecker
2007-01-01
This study was designed to assess the efficacy of an ionic toothbrush on reducing plaque and gingivitis. Twenty first-year dental students were included in the study. Ten individuals were randomly assigned to use either an ionic or a conventional toothbrush. Two periods of 28 days each were used with each brush, with a wash-out period of 14 days. A calibrated examiner used the Quigley-Hein Plaque Index (QHI) and Gingival Bleeding Index (GBI) on six sites per tooth, on all teeth, both pre- and post-brushing. The examiner was unaware of the toothbrush used by the subjects. Means were calculated, and for intra and inter-group comparisons a paired sample t-test was used (alpha = 0.05). On buccal-lingual surfaces, both toothbrushes significantly reduced plaque; there was no statistically significant difference between the two toothbrushes (1.56 and 1.52 for ionic and conventional toothbrushes, respectively). In interdental spaces, an increase of QHI was detected for both brushes, but without significant differences between them. For the GBI on buccal/lingual surfaces, no significant differences were detected between toothbrushes. The GBI did not significantly change for either toothbrush on interdental surfaces during the study period. The ionic and the conventional toothbrushes did not present statistically significant differences on plaque and gingival bleeding reductions.
Proceedings of the 1990 International Meeting on Reduced Enrichment for Research and Test Reactors
1993-07-01
The global effort to reduce, and possibly, eliminate the international traffic in highly-enriched uranium caused by its use in research reactors requires extensive cooperation and free exchange of information among all participants. To foster this free exchange of information, the Reduced Enrichment Research and Test Reactor (RERTR) Program, at Argonne National Laboratory, sponsored this meeting as the thirteenth of a series which began in 1978. The common effort brought together, past, a large number of specialists from many countries. On hundred twenty-three participants from 26 countries, including scientists, reactor operators, and personnel from commercial fuel suppliers, research centers, and government organizations, convened in Newport, Rhode Island to discuss their results, their activities, and their plans relative to converting research reactors to low-enriched fuels. As more and more reactors convert to the use of low-enriched uranium, the emphasis of our effort has begun to shift from research and development to tasks more directly related to implementation of the new fuels and technologies that have been developed, and to refinements of those fuels and technologies. It is appropriate, for this reason, that the emphasis of this meeting was placed on safety and on conversion experiences. This individual papers in this report have been cataloged separately.
Brewster, Sarah E; Elliott, Mark A; Kelly, Steve W
2015-01-01
Implementation intentions have the potential to break unwanted habits and help individuals behave in line with their goal intentions. We tested the effects of implementation intentions in the context of drivers' speeding behavior. A randomized controlled design was used. Speeding behavior, goal intentions and theoretically derived motivational pre-cursors of goal intentions were measured at both baseline and follow-up (one month later) using self-report questionnaires. Immediately following the baseline questionnaire, the experimental (intervention) group (N=117) specified implementation intentions using a volitional help sheet, which required the participants to link critical situations in which they were tempted to speed with goal-directed responses to resist the temptation. The control group (N=126) instead received general information about the risks of speeding. In support of the hypotheses, the experimental group reported exceeding the speed limit significantly less often at follow-up than did the control group. This effect was specific to 'inclined abstainers' (i.e., participants who reported speeding more than they intended to at baseline and were therefore motivated to reduce their speeding) and could not be attributed to any changes in goal intentions to speed or any other measured motivational construct. Also in line with the hypotheses, implementation intentions attenuated the past-subsequent speeding behavior relationship and augmented the goal intention - subsequent speeding behavior relationship. The findings imply that implementation intentions are effective at reducing speeding and that they do so by weakening the effect of habit, thereby helping drivers to behave in accordance with their existing goal intentions. The volitional help sheet used in this study is an effective tool for promoting implementation intentions to reduce speeding.
Nasser Pourmoallem
2013-01-01
factors•The variable of rescue coordination centers and road safety management methods [8]The Statistics used in this study is derived from published collections of “Traffic and Safety”, affiliated to the “Deputy of Traffic Police” and the "Traffic Control Center" of the city of Tehran. Analysis of the data has been conducted using the Expert Choice software and Analytic Hierarchy process.In scenario No. 2, the effective factors on traffic culture in the viewpoint of police officers and municipal authorities are investigated. In this part, the effective factors on the traffic culture have been studied from the viewpoints of the police administrators and officials together with those in the municipality of Najaf Abad in 1391.The three main and effective factors on the improvement of traffic include:•Cultural-social factors•Technical-financial factors•Organizational factorsIn scenario No. 3, the process of determining Isfahani citizens` educational needs with regard to traffic in the city is discussed. The purpose of this study was to determine the educational needs of citizens of Isfahani citizens in case of traffic. The research population of this research consists of all seven-year-old and above citizens, mostly residents of the 3rd, 6th, and 9th regions of the city of Isfahan in the time of the study. A number of 384 individuals from different educational backgrounds, various ages and different genders and jobs have been chosen; their opinions were collected and then analyzed using SPSS software.Discussion of Results & ConclusionConsidering the given results from the above scenarios, the following points can be noted:From the analysis of the factors involved in improving safety in the first scenario, it can be concluded that inclusive education to different casts of the society with a weight of approximately %50, plays the highest role in improving traffic safety.The factors of “imposing strict regulations”, “re-education and re-test courses”,
Balamurugan, P; Joshi, M Hiren; Rao, T S
2011-10-01
Culture and molecular-based techniques were used to characterize bacterial diversity in the cooling water system of a fast breeder test reactor (FBTR). Techniques were selected for special emphasis on sulphate-reducing bacteria (SRB). Water samples from different locations of the FBTR cooling water system, in addition to biofilm scrapings from carbon steel coupons and a control SRB sample were characterized. Whole genome extraction of the water samples and SRB diversity by group specific primers were analysed using nested PCR and denaturing gradient gel electrophoresis (DGGE). The results of the bacterial assay in the cooling water showed that the total culturable bacteria (TCB) ranged from 10(3) to 10(5) cfu ml(-1); iron-reducing bacteria, 10(3) to 10(5) cfu ml(-1); iron oxidizing bacteria, 10(2) to 10(3) cfu ml(-1) and SRB, 2-29 cfu ml(-1). However, the counts of the various bacterial types in the biofilm sample were 2-3 orders of magnitude higher. SRB diversity by the nested PCR-DGGE approach showed the presence of groups 1, 5 and 6 in the FBTR cooling water system; however, groups 2, 3 and 4 were not detected. The study demonstrated that the PCR protocol influenced the results of the diversity analysis. The paper further discusses the microbiota of the cooling water system and its relevance in biofouling.
Esser, Marissa B; Siegel, Michael
2014-11-01
Underage drinking accounts for 4400 alcohol-attributable deaths in the US each year. After several reports of the deaths of young people due to the consumption of the flavored-alcoholic beverage (FAB) Four Loko, the Federal Trade Commission (FTC) examined whether Phusion Projects violated federal law by using deceptive marketing. In 2013, the FTC responded by ordering alcohol facts labels on Four Loko disclosing the number of standard drinks contained in the product. This paper aims to discuss whether the FTC's order for alcohol facts labels on Four Loko cans will effectively reduce the hazardous consumption of FABs among youth. The authors discuss the existing research that relates to the FTC's order, including studies on the effectiveness of serving size labeling for reducing youth drinking, research on the brand-specific consumption of FABs among underage youth, and the associations between youth drinking and exposure to alcohol marketing. After synthesizing the evidence, the authors conclude that simply requiring the disclosure of the number of standard drinks on supersized Four Loko cans is not likely to adequately address the hazardous consumption of this beverage among underage drinkers. Instead, if the FTC addresses the marketing of these products and its potential to encourage the excessive use of alcohol, as the Attorneys General did recently in a settlement with the same company, it is possible that there would be a greater impact on reducing youth alcohol consumption. Additional research is needed to determine the impact of alcohol facts labels in changing underage drinking behaviors.
Chang Xu
2015-11-01
Full Text Available This paper investigates governor design by reduced-order sliding mode for a hydropower plant with an upstream surge tank. The governing system is made up of a tunnel, a surge tank, a penstock, a wicket gate and servomechanism, a governor, a hydro-turbine and a grid. Concerning the components of the governing system, their mathematic models are established. Then, these models are interconnected to simulate the governing system. From the viewpoint of state space in modern control theory, the governing system is partially observed, which challenges the governor design. By introducing an additional state variable, the control method of reduced-order sliding mode is proposed, where the governor design is based on a reduced-order governing system. Since the governor is applied to the original governing system, the system stability is analyzed by means of the small gain theorem. An genetic algorithm is employed to search a group of parameters of the predefined sliding surface, and a fuzzy inference system is utilized to decrease the chattering problem. Some numerical simulations are illustrated to verify the feasibility and robustness of the control method.
Batou, A., E-mail: anas.batou@univ-paris-est.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Soize, C., E-mail: christian.soize@univ-paris-est.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Brie, N., E-mail: nicolas.brie@edf.fr [EDF R and D, Département AMA, 1 avenue du général De Gaulle, 92140 Clamart (France)
2013-09-15
Highlights: • A ROM of a nonlinear dynamical structure is built with a global displacements basis. • The reduced order model of fuel assemblies is accurate and of very small size. • The shocks between grids of a row of seven fuel assemblies are computed. -- Abstract: We are interested in the construction of a reduced-order computational model for nonlinear complex dynamical structures which are characterized by the presence of numerous local elastic modes in the low-frequency band. This high modal density makes the use of the classical modal analysis method not suitable. Therefore the reduced-order computational model is constructed using a basis of a space of global displacements, which is constructed a priori and which allows the nonlinear dynamical response of the structure observed on the stiff part to be predicted with a good accuracy. The methodology is applied to a complex industrial structure which is made up of a row of seven fuel assemblies with possibility of collisions between grids and which is submitted to a seismic loading.
Singh, Kirmender; Bhattacharyya, A. B.
2017-03-01
Gummel Symmetry Test (GST) has been a benchmark industry standard for MOSFET models and is considered as one of important tests by the modeling community. BSIM4 MOSFET model fails to pass GST as the drain current equation is not symmetrical because drain and source potentials are not referenced to bulk. BSIM6 MOSFET model overcomes this limitation by taking all terminal biases with reference to bulk and using proper velocity saturation (v -E) model. The drain current equation in BSIM6 is charge based and continuous in all regions of operation. It, however, adopts a complicated method to compute source and drain charges. In this work we propose to use conventional charge based method formulated by Enz for obtaining simpler analytical drain current expression that passes GST. For this purpose we adopt two steps: (i) In the first step we use a modified first-order hyperbolic v -E model with adjustable coefficients which is integrable, simple and accurate, and (ii) In the second we use a multiplying factor in the modified first-order hyperbolic v -E expression to obtain correct monotonic asymptotic behavior around the origin of lateral electric field. This factor is of empirical form, which is a function of drain voltage (vd) and source voltage (vs) . After considering both the above steps we obtain drain current expression whose accuracy is similar to that obtained from second-order hyperbolic v -E model. In modified first-order hyperbolic v -E expression if vd and vs is replaced by smoothing functions for the effective drain voltage (vdeff) and effective source voltage (vseff), it will as well take care of discontinuity between linear to saturation regions of operation. The condition of symmetry is shown to be satisfied by drain current and its higher order derivatives, as both of them are odd functions and their even order derivatives smoothly pass through the origin. In strong inversion region and technology node of 22 nm the GST is shown to pass till sixth-order
Hu, Xiaoqing; Bergström, Zara M; Bodenhausen, Galen V; Rosenfeld, J Peter
2015-07-01
The present study investigated the extent to which people can suppress unwanted autobiographical memories in a memory-detection context involving a mock crime. Participants encoded sensorimotor-rich memories by enacting a lab-based crime (stealing a ring) and received instructions to suppress memory of the crime in order to evade guilt detection in a brain-wave-based concealed-information test. Aftereffects of suppression on automatic memory processes were measured in an autobiographical Implicit Association Test. Results showed that suppression attenuated brain-wave activity (the P300) associated with crime-relevant memory retrieval, which rendered waveforms from innocent and guilty participants indistinguishable. However, the two groups could nevertheless be discriminated via the late-posterior-negative slow wave, which may reflect the need to monitor response conflict arising between voluntary suppression and automatic recognition processes. Finally, extending recent findings that suppression can impair implicit memory processes, we provide novel evidence that suppression reduces automatic cognitive biases often associated with actual autobiographical memories. © The Author(s) 2015.
Nee, Robert J; Yang, Chich-Haung; Liang, Chung-Chao; Tseng, Guo-Fang; Coppieters, Michel W
2010-08-01
It is assumed that strain in a nerve segment at the end of a neurodynamic test will be greatest if the joint nearest that nerve segment is moved first in the neurodynamic test sequence. To test this assumption, the main movements of the median nerve biased neurodynamic test were applied in three different sequences to seven fresh-frozen human cadavers. Strain and longitudinal excursion were measured in the median nerve at the distal forearm. Strain and relative position of the nerve at the end of a test did not differ between sequences. The nerve was subjected to higher levels of strain for a longer duration during the sequence where wrist extension occurred first. The pattern of excursion was different for each sequence. The results highlight that order of movement does not affect strain or relative position of the nerve at the end of a test when joints are moved through comparable ranges of motion. When used clinically, different neurodynamic sequences may still change the mechanical load applied to a nerve segment. Changes in load may occur because certain sequences apply increased levels of strain to the nerve for a longer time period, or because sequences differ in ranges of joint motions.
Interpretation of spirometric tests in asthmatic patients with reduced forced vital capacity.
Almirall, J J; Páez, I
1994-01-01
We have studied 175 consecutive asthmatic patients presenting with: 1) a reversible airflow obstruction, demonstrated by an increase in the forced expiratory volume in 1 second (FEV1) or in the forced vital capacity (FVC) by at least 12% along with an absolute increase of 200 ml versus prebronchodilator values after inhalation of salbutamol; 2) FVC below the lower normal limit before administration of the bronchodilator; and 3) normal FVC or slow vital capacity after bronchodilator. Two different criteria for the lower normal limit of the FEV1/FVC ratio were used to determine whether prebronchodilator spirometric patterns could be considered obstructive or not. The use of the predicted FEV1/FVC ratio as the lower normal limit allowed correct identification of obstruction in 94.9% of the patients, whereas taking the estimated fifth percentile as the lower normal limit of the FEV1/FVC correctly identified obstruction in only 78.9% of the asthmatics. Our results suggest that the predicted FEV1/FVC ratio is an adequate estimate of the lower normal limit in asthmatic patients with reduced FVC in order to distinguish obstructive from nonobstructive patterns.
Deanovic, Linda A; Markiewicz, Dan; Stillway, Marie; Fong, Stephanie; Werner, Inge
2013-03-01
Standard U.S. Environmental Protection Agency laboratory tests are used to monitor water column toxicity in U.S. surface waters. The water flea Ceriodaphnia dubia is among the most sensitive test species for detecting insecticide toxicity in freshwater environments.Its usefulness is limited, however, when water conductivity exceeds 2,000 µS/cm (approximately 1 ppt salinity) and test effectiveness is insufficient. Water column toxicity tests using the euryhaline amphipod Hyalella azteca could complement C. dubia tests; however, standard chronic protocols do not exist. The present study compares the effectiveness of two water column toxicity tests in detecting the toxicity of two organophosphate (OP) and two pyrethroid insecticides: the short-term chronic C. dubia test, which measures mortality and fecundity, and a 10-d H. azteca test, which measures mortality and growth. Sensitivity was evaluated by comparing effect data, and end point variability was evaluated by comparing minimum significant differences. Tests were performed in synthetic water and filtered ambient water to quantify the influence of water matrix on effect concentrations. The H. azteca test detected pyrethroid toxicity far more effectively, while the C. dubia test was more sensitive to OPs. Among endpoints, H. azteca mortality was most robust. The results demonstrate that the H. azteca test is preferable when conductivity of water samples is 2,000 to 10,000 µS/cm or if contaminants of concern include pyrethroid insecticides.
Cripton, P A; Bruehlmann, S B; Orr, T E; Oxland, T R; Nolte, L P
2000-12-01
Presently, there is little consensus about how, or even if, axial preload should be incorporated in spine flexibility tests in order to simulate the compressive loads naturally present in vivo. Some preload application methods are suspected of producing unwanted "artefact" forces as the specimen rotates and, in doing so, influencing the resulting kinematics. The objective of this study was to quantitatively compare four distinct types of preload which have roots in contemporary experimental practice. The specific quantities compared were the reaction moments and forces resulting at the intervertebral disc and specimen kinematics. The preload types incorporated increasing amounts of caudal constraint on the preload application vector ranging from an unconstrained dead-load arrangement to an apparatus that allowed the vector to follow rotations of the specimen. Six human cadaveric spine segments were tested (1-L1/L2, 3-L2/L3, 1-L3/L4 and 1-L4/L5). Pure moments were applied to the specimens with each of the four different types of compressive preload. Kinematic response was measured using an opto-electronic motion analysis system. A six-axis load cell was used to measure reaction forces and moments. Artefact reaction moments and shear forces were significantly affected by preload application method and magnitude. Unconstrained preload methods produced high artefact moments and low artefact shear forces while more constrained methods did the opposite. A mechanical trade-off is suggested by our results, whereby unwanted moment can only be prevented at the cost of shear force production. When comparing spine flexibility studies, caution should be exercised to ensure preload was applied in a similar manner for all studies. Unwanted moments or forces induced as a result of preload application method may render the comparison of two seemingly similar studies inappropriate.
Haussaire, J.-M.; Bocquet, M.
2016-01-01
Bocquet and Sakov (2013) introduced a low-order model based on the coupling of the chaotic Lorenz-95 (L95) model, which simulates winds along a mid-latitude circle, with the transport of a tracer species advected by this zonal wind field. This model, named L95-T, can serve as a playground for testing data assimilation schemes with an online model. Here, the tracer part of the model is extended to a reduced photochemistry module. This coupled chemistry meteorology model (CCMM), the L95-GRS (generic reaction set) model, mimics continental and transcontinental transport and the photochemistry of ozone, volatile organic compounds and nitrogen oxides. Its numerical implementation is described. The model is shown to reproduce the major physical and chemical processes being considered. L95-T and L95-GRS are specifically designed and useful for testing advanced data assimilation schemes, such as the iterative ensemble Kalman smoother (IEnKS), which combines the best of ensemble and variational methods. These models provide useful insights prior to the implementation of data assimilation methods into larger models. We illustrate their use with data assimilation schemes on preliminary yet instructive numerical experiments. In particular, online and offline data assimilation strategies can be conveniently tested and discussed with this low-order CCMM. The impact of observed chemical species concentrations on the wind field estimate can be quantitatively assessed. The impacts of the wind chaotic dynamics and of the chemical species non-chaotic but highly nonlinear dynamics on the data assimilation strategies are illustrated.
Does a Negative Triple Test Reduce the Rate of Negative Appendectomy in Adults?
Mahmoud F. Sakr
2012-08-01
Results: Sixty-seven patients (65.9% were female and 35 (34.1% were male. Their ages ranged between 16 and 49 years (mean 27.5 years. Most patients (87.3% had their symptoms for 12-36 hours before hospital admission. The mean values for TLC, NP, and CRP were 7,573/ and micro;L, 54.53%, and 0.61 mg/L, respectively. Of the 102 patients with NTT, 101 (99% proved not to have appendiceal inflammation (NPV=99%. Only 39 patients were operated upon, of whom 38 (97.4% had a normal appendix, and the remaining 63 patients were either discharged (n=47 or referred to other specialties (n=16. There were significantly more women (76.3%, 29/38 with negative appendectomy than men (24.7%, 9/38 (X2= 21.1, p=0.0001. Gynecological causes were the most common (60.5%, 23/38 and in 11 cases, the exact etiology could not be identified. Conclusions: From the data presented, it may be concluded that TLC, NP and CRP blood levels (triple test should be measured upon hospital admission of adult patients with clinically suspected acute appendicitis. If used judiciously, they may spare the group of patients with an NTT an unnecessary surgical operation, hence markedly reducing the NAR with its potential risks. [Arch Clin Exp Surg 2012; 1(4.000: 229-236
A test of reactive scope: Reducing reactive scope causes delayed wound healing.
DuRant, S E; Arciniega, M L; Bauer, C M; Romero, L M
2016-09-15
Reactive scope predicts that all animals have an adaptive ability to respond to stressors in their environment, termed reactive homeostasis, and that only when an animal's response to stressful stimuli exceeds a certain threshold (homeostatic overload) will stress have pathological effects. While this framework has successfully helped interpret effects of stressors on wildlife, no study has designed an experiment to directly test this framework. This study was designed to expose house sparrows (Passer domesticus) to treatments that would result in varying ranges of reactive homeostasis during chronic stress, which based on the reactive scope model should cause birds with the lowest reactive homeostasis range to exhibit signs of pathology during a subsequent challenge. To modulate the reactive homeostasis range, we altered allostatic load of birds by exposing them to chronic stress while either elevating, blocking, or not manipulating corticosterone. After concluding chronic stress treatments, birds were exposed to the subsequent challenge of a superficial wound. Individuals treated with corticosterone during chronic stress (high allostatic load) experienced the most pathology, including both weight loss and slower wound healing. Unmanipulated birds (medium allostatic load) also experienced weight loss but had normal healing rates, while birds with blocked corticosterone (low allostatic load) had minimal weight loss and normal healing rates. Our results indicate that increased allostatic load reduces the reactive homeostasis range, thereby causing individuals to cross the homeostatic overload threshold sooner, and thus support the reactive scope framework.
Lammen, Yannick; Reinacher, Andreas; Brewster, Rick; Greiner, Benjamin; Graf, Friederike; Krabbe, Alfred
2016-07-01
The Stratospheric Observatory For Infrared Astronomy (SOFIA) reached its full operational capability in 2014 and takes off from the NASA Armstrong Flight Research Center to explore the universe about three times a week. Maximizing the program's scientific output naturally leaves very little flight time for implementation and test of improved soft- and hardware. Consequently, it is very important to have a comparable test environment and infrastructure to perform troubleshooting, verifications and improvements on ground without interfering with science missions. SOFIA's Secondary Mirror Mechanism is one of the most complex systems of the observatory. In 2012 a first simple laboratory mockup of the mechanism was built to perform basic controller tests in the lower frequency band of up to 50Hz. This was a first step to relocate required engineering tests from the active observatory into the laboratory. However, to test and include accurate filters and damping methods as well as to evaluate hardware modifications a more precise mockup is required that represents the system characteristics over a much larger frequency range. Therefore the mockup has been improved in several steps to a full test environment representing the system dynamics with high accuracy. This new ground equipment allows moving almost the entire secondary mirror test activities away from the observatory. As fast actuator in the optical path, the SMM also plays a major role in SOFIA's pointing stabilization concept. To increase the steering bandwidth, hardware changes are required that ultimately need to be evaluated using the telescope optics. One interesting concept presented in this contribution is the in- stallation of piezo stack actuators between the mirror and the chopping mechanism. First successful baseline tests are presented. An outlook is given about upcoming performance tests of the actively controlled piezo stage with local metrology and optical feedback. To minimize the impact on
He Shu-Li; Peng Yin; Liu Li-Li; Jiang Hong-Wei; Liu Li-Feng; Zheng Wu; Wang Ai-Ling
2007-01-01
In this paper, Fe3oPt70/Fe3O4 core/shell nanoparticles were synthesized by chemical routine and the layered polycthylenimine (PEI)-Fe30Pt70/Fe3O4 structure was constructed by molecule-mediated self-assembly technique. The dimension of core/shell structured nanoparticles was that of 4nm core and 2 nm shell. After annealing under a flow of forming gas (50%Ar2%%30%H2) for 1h at or above 400℃, the iron oxide shell was reduced to Fe and diffused to Pt-rich core, which leaded to the formation of L10 phase FePt at low temperature. The x-ray diffraction results and magnetic properties measurement showed that the chemical ordering temperature of Fe30Pt70/Fe3O4 core/shell nanoparticles assembly can be reduced to as low as 400℃. The sample annealed at 400℃ showed the coercivity of 4 KOe with the applied field of 1.5T. The core/shell structure was suggested to be an effective way to reduce the ordering temperature obviously.
Mac-Beath, I.; Castillo, S.; Camposeco, R.; Moran-Pineda, M. [Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico). Programa de Ingenieria Molecular
2010-07-01
In this work, three-way catalytic systems (TWC-K, TWC-M and TWC-P) were prepared and tested experimentally in order to analyze N{sub 2}O emissions. Various types and quantities of precious metals (Pt-Pd-Rh), and different mixed oxides (CexBayLazMgwO{sub 2}-Al{sub 2}O{sub 3}) to prepare the supports were used. The catalytic tests were carried out by using common exhaust gases from a gasoline engine under different oxidizing conditions. The TWC catalytic compositions were based on catalytic converters used in retrofitting programs in the Metropolitan Area in Mexico City. Fresh and aged TWC catalytic samples were tested; in both conditions, the catalytic compositions were characterized by BET, TEM-EDS and XRD in order to analyze the efficiency of the catalytic behavior. Due to the fact that the 4{sup th} TWC generation (Pd-Only TWC) has Pd as main active metal, the tested TWC catalytic samples were synthesized by having Pd in a higher proportion with regard to Pt and Rh used as complements with some differences in support composition. (orig.)
Khng, Kiat Hui
2016-09-26
A pre-test/post-test, intervention-versus-control experimental design was used to examine the effects, mechanisms and moderators of deep breathing on state anxiety and test performance in 122 Primary 5 students. Taking deep breaths before a timed math test significantly reduced self-reported feelings of anxiety and improved test performance. There was a statistical trend towards greater effectiveness in reducing state anxiety for boys compared to girls, and in enhancing test performance for students with higher autonomic reactivity in test-like situations. The latter moderation was significant when comparing high-versus-low autonomic reactivity groups. Mediation analyses suggest that deep breathing reduces state anxiety in test-like situations, creating a better state-of-mind by enhancing the regulation of adaptive-maladaptive thoughts during the test, allowing for better performance. The quick and simple technique can be easily learnt and effectively applied by most children to immediately alleviate some of the adverse effects of test anxiety on psychological well-being and academic performance.
Tajudin Noor
2015-05-01
Full Text Available Pecking Order Theory (POT states that hierarchy fundings based on the cheapest cost coming from internal fund, followed by external fund are needed to determine the capital structure. The research objectives were to examine the concept of POT in agriculture companies listed on Indonesia Stock Exchange in order to decide the capital structure policies as well as to analyse the effects of company’s characteristics to the emitten capital structure. The research used regression analysis with pooled least square (PLS method in order to test POT, while the fixed effect model (FEM was applied to analyze the effect of company’s characteristics on capital structure. Regression analysis in evaluating pecking order theory’s concept shows that internal funding deficit significantly gives positive influence to the change of long term debts. Regression analysis resulted from company’s characteristics (profitability, size, growth, tangibility and liquidity shows that the company’s size and growth have significant positive effects on capital structure (leverage, whereas company’s profitability and liquidity have significant negative effects on capital structure (leverage. By contrast, company’s assets structure (tangibility do not give significantly influence on capital structure (leverage in 10% level of significance. The research shows that issuers in agricultural sector have implemented the concept of POT through the hierarchy usage of the cheapest financing from the internal as a priority followed by the external financing (debt.Keywords: Pecking Order Theory, capital structure, company’s characteristics, PLS, FEMABSTRAKPecking Order Theory menyatakan bahwa penentuan struktur modal yang optimal didasarkan pada keputusan pendanaan secara hirarki berdasarkan biaya modal yang paling murah yang bersumber pada dana internal, baru kemudian menggunakan sumber dana eksternal. Penelitian ini bertujuan menguji penggunaan konsep Pecking Order Theory
Kikuchi, Ryota; Misaka, Takashi; Obayashi, Shigeru
2016-04-01
An integrated method consisting of a proper orthogonal decomposition (POD)-based reduced-order model (ROM) and a particle filter (PF) is proposed for real-time prediction of an unsteady flow field. The proposed method is validated using identical twin experiments of an unsteady flow field around a circular cylinder for Reynolds numbers of 100 and 1000. In this study, a PF is employed (ROM-PF) to modify the temporal coefficient of the ROM based on observation data because the prediction capability of the ROM alone is limited due to the stability issue. The proposed method reproduces the unsteady flow field several orders faster than a reference numerical simulation based on Navier-Stokes equations. Furthermore, the effects of parameters, related to observation and simulation, on the prediction accuracy are studied. Most of the energy modes of the unsteady flow field are captured, and it is possible to stably predict the long-term evolution with ROM-PF.
Engineering Macaca fascicularis cytochrome P450 2C20 to reduce animal testing for new drugs.
Rua, Francesco; Sadeghi, Sheila J; Castrignanò, Silvia; Di Nardo, Giovanna; Gilardi, Gianfranco
2012-12-01
In order to develop in vitro methods as an alternative to P450 animal testing in the drug discovery process, two main requisites are necessary: 1) gathering of data on animal homologues of the human P450 enzymes, currently very limited, and 2) bypassing the requirement for both the P450 reductase and the expensive cofactor NADPH. In this work, P450 2C20 from Macaca fascicularis, homologue of the human P450 2C8 has been taken as a model system to develop such an alternative in vitro method by two different approaches. In the first approach called "molecular Lego", a soluble self-sufficient chimera was generated by fusing the P450 2C20 domain with the reductase domain of cytochrome P450 BM3 from Bacillus megaterium (P450 2C20/BMR). In the second approach, the need for the redox partner and also NADPH were both obviated by the direct immobilization of the P450 2C20 on glassy carbon and gold electrodes. Both systems were then compared to those obtained from the reconstituted P450 2C20 monooxygenase in presence of the human P450 reductase and NADPH using paclitaxel and amodiaquine, two typical drug substrates of the human P450 2C8. The K(M) values calculated for the 2C20 and 2C20/BMR in solution and for 2C20 immobilized on electrodes modified with gold nanoparticles were 1.9 ± 0.2, 5.9 ± 2.3, 3.0 ± 0.5 μM for paclitaxel and 1.2 ± 0.2, 1.6±0.2 and 1.4 ± 0.2 μM for amodiaquine, respectively. The data obtained not only show that the engineering of M. fascicularis did not affect its catalytic properties but also are consistent with K(M) values measured for the microsomal human P450 2C8 and therefore show the feasibility of developing alternative in vitro animal tests. Copyright © 2012 Elsevier Inc. All rights reserved.
Wray, Patrick; Li, Jing; Li, Ling Qiao; Kazarian, Sergei G
2014-07-01
In this study of multi-layer tablets, the dissolution of biphasic and zero-order release formulations has been studied primarily using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging as well as UV-Vis detection of dissolved drug in the effluent stream and USP dissolution testing. Bilayer tablets, containing the excipients microcrystalline cellulose (MCC) and glucose, were used for biphasic release with nicotinamide and buflomedil as model drugs. ATR-FTIR spectroscopic imaging showed the changing component distributions during dissolution. Further experiments studied monolithic and barrier-layered tablets containing hydroxypropyl methylcellulose, MCC and buflomedil dissolving in a USP I apparatus. These data were compared with UV-Vis dissolution profiles obtained online with the ATR flow-through cell. ATR-FTIR imaging data of the biphasic formulations demonstrated that the drug release was affected by excipient ratios and effects such as interference between tablet sections. Tablets placed in the ATR-FTIR flow-through cell exhibited zero-order UV-Vis dissolution profile data at high flow rates, similar to barrier-layered formulations studied using the USP I apparatus. ATR-FTIR spectroscopic imaging provided information regarding the dissolution mechanisms in multi-layer tablets which could assist formulation development. The ability to relate data from USP dissolution tests with that from the ATR-FTIR flow-through cell could help spectroscopic imaging complement dissolution methods used in the industry.
Fike, Jeffrey A.
2013-08-01
The construction of stable reduced order models using Galerkin projection for the Euler or Navier-Stokes equations requires a suitable choice for the inner product. The standard L2 inner product is expected to produce unstable ROMs. For the non-linear Navier-Stokes equations this means the use of an energy inner product. In this report, Galerkin projection for the non-linear Navier-Stokes equations using the L2 inner product is implemented as a first step toward constructing stable ROMs for this set of physics.
Repetitive Cyclic Potentiodynamic Polarization Scan Results for Reduced Sample Volume Testing
LaMothe, Margaret E. [Washington River Protection Solutions, Richland, WA (United States)
2016-03-15
This report is the compilation of data gathered after repetitively testing simulated tank waste and a radioactive tank waste sample using a cyclic potentiodynamic polarization (CPP) test method to determine corrosion resistance of metal samples. Electrochemistry testing of radioactive tank samples is often used to assess the corrosion susceptibility and material integrity of waste tank steel. Repetitive testing of radiological tank waste is occasionally requested at 222-S Laboratory due to the limited volume of radiological tank sample received for testing.
BAI Sha; P. Bambade; WANG Dou; GAO Jie; M. Woodley; M. Masuzawa
2012-01-01
The ATF2 project is the final focus system prototype for the ILC and CLIC linear collider projects,with the purpose of reaching a 37nm vertical beam size at the interaction point.In the nanometer beam size regime,higher order multipoles in magnets become a crucial point for consideration.The strength and rotation angle of the ATF2 QEA magnets were reconstructed from the IHEP measurements and compared with the KEK ones to be identical.Based on the study of the skew multipoles sensitivity,we report on the analysis of the possible mitigation of the measured multipoles.A suggestion is given which will benefit the ATF2 present commissioning to reach the goal beam size,and also the reduced β optics in future.
Melo, Magaly Carvalho Vieira de; Ximenes, Ricardo Arraes de Alencar; Falcão, Ilka Veras; Miranda-Filho, Demócrito de Barros
2017-08-01
The implementation of rapid HIV testing in Brazil began in 2006 for specific groups, and from 2009 was extended to the Counseling and Testing Centers (CTC) in certain Brazilian capitals. The aim of this study was to compare two groups of individuals: those diagnosed with HIV infection by conventional testing and those diagnosed with rapid testing, with respect to: the waiting time before receiving medical care, the time of the first laboratory tests and the virological, immune and clinical status. This is a cross-sectional study to compare a group with individuals diagnosed by conventional testing (2006-2008) and another with those diagnosed by rapid testing (2010-2011).The median time between blood collection and diagnosis of HIV in the conventional test group was 76 days, while in the rapid test group 94.2% of the subjects received their results on the same day of blood collection (p rapid test group the time was 14 days (p rapid test group (p rapid test group (472) was higher than in the conventional test group (397) (p = 0.01). The introduction of rapid HIV testing as a diagnostic strategy has reduced the waiting times for medical care and laboratory tests and also allowed earlier diagnosis of HIV infection than with the conventional test.
Wen-Hung; Hsu; Sophie; SW; Wang; Chiao-Yun; Chen; Ching-Wen; Chang; Jaw-Yuan; Wang; Yuan-Chieh; Yang; Deng-Chyang; Wu; Ming-Tsang; Wu
2010-01-01
AIM:To evaluate the influence of multiple samplings during esophagogastr oduodenoscopy(EGD) on the accuracy of the rapid urease test,and the validity of newly developed rapid urease tests,HelicotecUT plus test and HelicotecUT test,CLO test and ProntoDry test.METHODS:A total of 355 patients undergoing EGD for dyspepsia were included.Their Helicobacter pylori(H.pylori) treatment status was either nave or eradicated.Six biopsy specimens from antrum and gastric body,respectively,were obtained during EGD.Single...
Mehmet Kaya
2015-01-01
This study aims to investigate the effect of psycho-education program on reducing the test anxiety and personal indecisiveness. The study was carried out with a group of ten 8th class volunteer students whose test anxiety scores were high. The test anxiety which is one of the study's variables was tested with Test Anxiety Inventory (TAI) that is adapted to Turkish by Öner (1990). Besides, Personal Indecisiveness Scale (PIS) that was developed by Bacanli (2000) was applied. The Psyco-education...
Pürrer, Michael
2015-01-01
I provide a frequency domain reduced order model (ROM) for the aligned-spin effective-one-body (EOB) model "SEOBNRv2" for data analysis with second and third generation ground based gravitational wave (GW) detectors. SEOBNRv2 models the dominant mode of the GWs emitted by the coalescence of black hole (BH) binaries. The large physical parameter space (dimensionless spins $-1 \\leq \\chi_i \\leq 0.99$ and symmetric mass-ratios $0.01 \\leq \\eta \\leq 0.25$) requires sophisticated reduced order modeling techniques, including patching in the parameter space and in frequency. I find that the time window over which the inspiral-plunge and the merger-ringdown waveform in SEOBNRv2 are connected is discontinuous when the spin of the deformed Kerr BH $\\chi=0.8$ or the symmetric mass-ratio $\\eta \\sim 0.083$. This discontinuity increases resolution requirements for the ROM. The ROM can be used for compact binary systems with total masses of $2 M_\\odot$ or higher for the advanced LIGO (aLIGO) design sensitivity and a $10$ Hz l...
Integrated Vibration and Acceleration Testing to Reduce Payload Mass, Cost and Mission Risk Project
National Aeronautics and Space Administration — We propose to develop a capability to provide integrated acceleration, vibration, and shock testing using a state-of-the-art centrifuge, allowing for the test of...
Price, Elsa C.
A study was conducted to determine the effectiveness of a Stress Management Seminar and a Test-Taking Skills Workshop in improving the scores of pre-nursing and guidance examinees at Wallace Community College in Dothan, Alabama. The 73 subjects took the Pre-Nursing and Guidance Examination (PNGE) in June 1984, September 1984, or January 1985.…
Consumption of reduced-fat products, haemostatic parameters and oral glucose tolerance test
Velthuis - Wierik, E.J.M. te; Kluft, C.; Berg, H. van den; Weststrate, J.A.
1996-01-01
A high fat intake has been associated with the high prevalence of coronary heart disease (CHD) in most Western countries. Consumption of reduced-fat products might reduce fat intake and beneficially affect markers of CHD risk. Therefore, the effects of 6 months of realistic consumption of
Kruse Christensen, Nikolaj; Christensen, Steen; Ferre, Ty Paul A.
2016-05-01
In spite of geophysics being used increasingly, it is often unclear how and when the integration of geophysical data and models can best improve the construction and predictive capability of groundwater models. This paper uses a newly developed HYdrogeophysical TEst-Bench (HYTEB) that is a collection of geological, groundwater and geophysical modeling and inversion software to demonstrate alternative uses of electromagnetic (EM) data for groundwater modeling in a hydrogeological environment consisting of various types of glacial deposits with typical hydraulic conductivities and electrical resistivities covering impermeable bedrock with low resistivity (clay). The synthetic 3-D reference system is designed so that there is a perfect relationship between hydraulic conductivity and electrical resistivity. For this system it is investigated to what extent groundwater model calibration and, often more importantly, model predictions can be improved by including in the calibration process electrical resistivity estimates obtained from TEM data. In all calibration cases, the hydraulic conductivity field is highly parameterized and the estimation is stabilized by (in most cases) geophysics-based regularization. For the studied system and inversion approaches it is found that resistivities estimated by sequential hydrogeophysical inversion (SHI) or joint hydrogeophysical inversion (JHI) should be used with caution as estimators of hydraulic conductivity or as regularization means for subsequent hydrological inversion. The limited groundwater model improvement obtained by using the geophysical data probably mainly arises from the way these data are used here: the alternative inversion approaches propagate geophysical estimation errors into the hydrologic model parameters. It was expected that JHI would compensate for this, but the hydrologic data were apparently insufficient to secure such compensation. With respect to reducing model prediction error, it depends on the type
Abbiendi, G; Alexander, Gideon; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bellerive, A; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bloodworth, Ian J; Bock, P; Böhme, J; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couchman, J; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Davis, R; De Jong, S; de Roeck, A; Dervan, P J; Desch, Klaus; Dienes, B; Dixit, M S; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Estabrooks, P G; Etzion, E; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fleck, I; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon-Shotkin, S M; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Harder, K; Harel, A; Hargrove, C K; Harin-Dirac, M; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hobson, P R; Höcker, Andreas; Hoffman, K; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Jones, C R; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J I; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klier, A; Kobayashi, T; Kobel, M; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kühl, T; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lauber, J; Lawson, I; Layter, J G; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Lü, J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mader, W F; Mannelli, M; Marcellini, S; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Méndez-Lorenzo, P; Merritt, F S; Mes, H; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Okpara, A N; Oreglia, M J; Orito, S; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Quadt, A; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Sproston, M; Stahl, A; Stephens, K; Steuerer, J; Stoll, K; Strom, D; Ströhmer, R; Surrow, B; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomas, J; Thomson, M A; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Van Kooten, R; Vannerem, P; Verzocchi, M; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; Wetterling, D; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Zacek, V; Zer-Zion, D
1999-01-01
We present a test of the flavour independence of the strong coupling constant for charm and bottom quarks with respect to light (uds) quarks, based on a hadronic event sample obtained with the OPAL detector at LEP. Five observables related to global event shapes were used to measure alpha_s in three flavour tagged samples (uds, c and b). The event shape distributions were fitted by Order(alpha_s**2) calculations of jet production taking into account mass effects for the c and b quarks. We find: = 0.997 +- 0.038(stat.) +- 0.030(syst.) +- 0.012(theory) and = 0.993 +- 0.008(stat.) +- 0.006(syst.) +- 0.011(theory) for the ratios alpha_s(charm)/alpha_s(uds) and alpha_s(b)/alpha_s(uds) respectively.
Christian, Pierre; Loeb, Abraham
2015-01-01
One avenue for testing the no-hair theorem is obtained through timing a pulsar orbiting close to a black hole and fitting for quadrupolar effects on the time-of-arrival of pulses. If deviations from the Kerr quadrupole are measured, then the no-hair theorem is invalidated. To this end, we derive an expression for the light travel time delay for a pulsar orbiting in a black-hole spacetime described by the Butterworth-Ipser metric, which has an arbitrary spin and quadrupole moment. We consider terms up to the quadrupole order in the black-hole metric and derive the time-delay expression in a closed analytic form. This allows for fast computations that are useful in fitting time-of-arrival observations of pulsars orbiting close to astrophysical black holes.
Leung, Erika; Song, Shuang; Al-Abboud, Omar; Shams, Shahed; English, John; Naji, Wisam; Huang, Yafei; Robison, Leon; Balis, Fred; Kawsar, Hameem I
2017-07-01
At our resident-run clinic in an underserved community, laboratory test costs in 2013 exceeded the government subsidy by $400 000. To optimize limited resources and improve patient care, an education program to reduce testing was implemented. Between November 2014 and January 2015, residents attended lectures on utilization of laboratory testing, focusing on standard practice guidelines, and analyses of unnecessary tests. Multivariate nonparametric statistical methods and subgroup analysis were used to evaluate cost reduction. There were 453 clinic visits during the intervention period and 471 visits during the control period. Lectures were independently associated with a significant laboratory cost reduction. Median laboratory cost per visit decreased from $106.00 to $74.00. Total cost in the study period decreased from $79 403 to $51 463. There were similar reductions of laboratory costs in two subgroups: age groups of <50 years and ≥50 years, new encounters, and follow-up visits . In the analysis of individual tests, the cost of TSH and Vitamin D tests had the greatest reduction ($8176 and $5088 respectively). An appropriate physician education program can reduce laboratory tests and costs. Screening tests with inadequate evidence support were reduced most, whereas those with proven benefits did not decrease significantly.
Reducing animal experimentation in foot-and-mouth disease vaccine potency tests.
Reeve, Richard; Cox, Sarah; Smitsaart, Eliana; Beascoechea, Claudia Perez; Haas, Bernd; Maradei, Eduardo; Haydon, Daniel T; Barnett, Paul
2011-07-26
The World Organisation for Animal Health (OIE) Terrestrial Manual and the European Pharmacopoeia (EP) still prescribe live challenge experiments for foot-and-mouth disease virus (FMDV) immunogenicity and vaccine potency tests. However, the EP allows for other validated tests for the latter, and specifically in vitro tests if a "satisfactory pass level" has been determined; serological replacements are also currently in use in South America. Much research has therefore focused on validating both ex vivo and in vitro tests to replace live challenge. However, insufficient attention has been given to the sensitivity and specificity of the "gold standard"in vivo test being replaced, despite this information being critical to determining what should be required of its replacement. This paper aims to redress this imbalance by examining the current live challenge tests and their associated statistics and determining the confidence that we can have in them, thereby setting a standard for candidate replacements. It determines that the statistics associated with the current EP PD(50) test are inappropriate given our domain knowledge, but that the OIE test statistics are satisfactory. However, it has also identified a new set of live animal challenge test regimes that provide similar sensitivity and specificity to all of the currently used OIE tests using fewer animals (16 including controls), and can also provide further savings in live animal experiments in exchange for small reductions in sensitivity and specificity.
Internalized homophobia and reduced HIV testing among men who have sex with men in China.
Pyun, Thomas; Santos, Glenn-Milo; Arreola, Sonya; Do, Tri; Hebert, Pato; Beck, Jack; Makofane, Keletso; Wilson, Patrick A; Ayala, George
2014-03-01
Although previous research has examined barriers and facilitators of HIV testing among men who have sex with men (MSM) in China, few studies have focused on social factors, including homophobia and internalized homophobia. This study utilized data from a global online survey to determine correlates of HIV testing as part of a subanalysis focused on Chinese MSM. Controlling for age, HIV knowledge, number of sexual partners, and other covariates, ever having tested for HIV was significantly correlated with lower internalized homophobia. This study suggests that stigma associated with sexual orientation may serve as a barrier to participation in HIV testing and other health-promoting behaviors.
Development and field testing of a self-assessment guide for computer-based provider order entry.
Vartian, Carl V; Singh, Hardeep; Russo, Elise; Sittig, Dean F
2014-01-01
Despite the benefits of computerized provider order entry (CPOE), numerous reports of unexpected CPOE-related safety concerns have surfaced. As part of a larger project to improve the safety of electronic health records (EHRs), we developed and field tested a CPOE "safety self-assessment" guide through literature searches, expert opinion, and site visits. We then conducted a field test of this guide with nine hospital chief medical informatics officers (CMIOs), who were identified through the Association of Medical Directors of Information Systems. The CPOE safety self-assessment guide was sent electronically to the CMIOs. Once the assessments were returned, we conducted structured telephone interviews for further comments about the guide's format and content. The CMIOs in our study found the CPOE safety guide useful and relatively easy to complete, taking no more than 30 minutes. Analysis of responses to the guide suggest that most recommended practices were implemented inconsistently across facilities. Despite consensus for certain CPOE best practices in the medical literature and among experts, there appeared to be considerable variation among CMIOs' opinions of best practices. Interview data suggested this inconsistency was mostly due to system limitations and/or differing opinions about the necessity of certain EHR-related safety measures. Despite the absence of consensus on best practices, a self-assessment safety guide provides a practical starting point for organizations to assess and improve safety and the effectiveness of their CPOE system.
Reduced Capacity in a Dichotic Memory Test for Adult Patients with ADHD
Dige, Niels; Maahr, Eija; Backenroth-Ohsako, Gunnel
2010-01-01
Objective: To evaluate whether a dichotic memory test would reveal deficits in short-term working-memory recall and long-term memory recall in a group of adult patients with ADHD. Methods: A dichotic memory test with ipsilateral backward speech distraction in an adult ADHD group (n = 69) and a control group (n = 66) is used to compare performance…
Reducing Test Anxiety among School-Aged Adolescents: A Field Experiment
Putwain, Dave; Chamberlain, Suzanne; Daly, Anthony L.; Sadreddini, Shireen
2014-01-01
This paper evaluates the effectiveness of a multimodal and information technology (IT)-delivered intervention for test anxiety. Participants were randomly allocated to an intervention or waiting list group. Test anxiety was measured pre- and post-intervention and academic buoyancy, a construct that refers to students' capacity to withstand…
Stetzel, KD; Aldrich, LL; Trimboli, MS; Plett, GL
2015-03-15
This paper addresses the problem of estimating the present value of electrochemical internal variables in a lithium-ion cell in real time, using readily available measurements of cell voltage, current, and temperature. The variables that can be estimated include any desired set of reaction flux and solid and electrolyte potentials and concentrations at any set of one-dimensional spatial locations, in addition to more standard quantities such as state of charge. The method uses an extended Kalman filter along with a one-dimensional physics-based reduced-order model of cell dynamics. Simulations show excellent and robust predictions having dependable error bounds for most internal variables. (C) 2014 Elsevier B.V. All rights reserved.
Paul W Ayers; Mel Levy
2005-09-01
Using the constrained search and Legendre-transform formalisms, one can derive ``generalized” density-functional theories, in which the fundamental variable is either the electron pair density or the second-order reduced density matrix. In both approaches, the -representability problem is solved by the functional, and the variational principle is with respect to all pair densities (density matrices) that are nonnegative and appropriately normalized. The Legendre-transform formulation provides a lower bound on the constrained-search functional. Noting that experience in density-functional and density-matrix theories suggests that it is easier to approximate functionals than it is to approximate the set of -representable densities sheds some light on the significance of this work.
Bonfiglio, Paolo; Pompoli, Francesco; Lionti, Riccardo
2016-04-01
The transfer matrix method is a well-established prediction tool for the simulation of sound transmission loss and the sound absorption coefficient of flat multilayer systems. Much research has been dedicated to enhancing the accuracy of the method by introducing a finite size effect of the structure to be simulated. The aim of this paper is to present a reduced-order integral formulation to predict radiation efficiency and radiation impedance for a panel with equal lateral dimensions. The results are presented and discussed for different materials in terms of radiation efficiency, sound transmission loss, and the sound absorption coefficient. Finally, the application of the proposed methodology for rectangular multilayer systems is also investigated and validated against experimental data.
Low-Cost, Class D Testing of Spacecraft Photovoltaic Systems Can Reduce Risk
Forgione, Joshua B.; Kojima, Gilbert K.; Hanel, Robert; Mallinson, Mark
2014-01-01
The end-to-end verification of a spacecraft photovoltaic power generation system requires light! A lowcost, portable, and end-to-end photovoltaic-system test appropriate for NASA's new generation of Class D missions is presented. High risk, low-cost, and quick-turn satellites rarely have the resources to execute the traditional approaches from higher-class (A-C) missions. The Class D approach, as demonstrated on the Lunar Atmospheric and Dust Environment Explorer (LADEE), utilizes a portable, metalhalide, theatre lamp for an end-to-end photovoltaic system test. While not as precise and comprehensive as the traditional Large Area Pulsed Solar Simulator (LAPSS) test, the LADEE method leverages minimal resources into an ongoing assessment program that can be applied through numerous stages of the mission. The project takes a true Class D approach in assessing the technical value of a costly, highfidelity performance test versus a simpler approach with less programmatic risk. The resources required are a fraction of that for a LAPSS test, and is easy to repeat due to its portability. Further, the test equipment can be handed down to future projects without building an on-site facility. At the vanguard of Class D missions, the LADEE team frequently wrestled with and challenged the status quo. The philosophy of risk avoidance at all cost, typical to Class A-C missions, simply could not be executed. This innovative and simple testing solution is contextualized to NASA Class D programs and a specific risk encountered during development of the LADEE Electrical Power System (EPS). Selection of the appropriate lamp and safety concerns are discussed, with examples of test results. Combined with the vendor's panellevel data and periodic inspection, the method ensures system integrity from Integration and Test (I&T) through launch. Following launch, mission operations tools are utilized to assess system performance based on a scant amount of available data.
Balajewicz, Maciej; Dowell, Earl
2015-01-01
For a projection-based reduced order model (ROM) to be stable and accurate, the dynamics of the truncated subspace must be taken into account. This paper proposes an approach for stabilizing and enhancing projection-based fluid ROMs in which truncated modes are accounted for \\textit{a priori} via a minimal rotation of the projection subspace. Attention is focused on the full non-linear compressible Navier-Stokes equations in specific volume form as a step toward a more general formulation for problems with generic non-linearities. Unlike traditional approaches, no empirical turbulence modeling terms are required, and consistency between the ROM and the full order model from which the ROM is derived is maintained. Mathematically, the approach is formulated as a quadratic matrix program on the Stiefel manifold. The reproductive as well as predictive capabilities of the method are evaluated on several compressible flow problems, including a problem involving laminar flow over an airfoil with a high angle of atta...
Li, Mian; Bo, Xiangjie; Zhang, Yufan; Han, Ce; Guo, Liping
2014-10-01
Iron phthalocyanine (FePc) is combined with different carbon matrixes (reduced graphene oxide (RGO), mesoporous carbon vesicle (MCV), and ordered mesoporous carbon (OMC)) through non-covalent π-π interaction. The nitrogen adsorption-desorption isotherms display that their specific surface areas obey an order of OMC > MCV > RGO. Raman spectroscopy reveals that OMC contains the most surface active sites. Meanwhile, SEM images show that the FePc monomers are more evenly dispersed on OMC than on MCV or RGO. Electrochemical measurements also display that oxygen reduction reaction (ORR) is catalyzed more easily on the FePc/OMC than on the FePc, FePc/MCV, and FePc/RGO, undoubtedly testifying the importances of specific surface area and surface active sites of OMC matrix for uniformly dispersing FePc molecules and then improving the ORR performances. Particularly, experiment results reveal that the FePc/OMC catalyst displays an enhanced 4-electron pathway in ORR either in acid or in alkaline media. Meanwhile, the FePc/OMC also shows better durability and superior stability towards methanol crossover than the Pt/OMC catalyst in both acid and alkaline media, potentially making the FePc/OMC a non-precious metal catalyst for ORR in fuel cells.
Low-Cost, Class D Testing of Spacecraft Photovoltaic Systems Can Reduce Risk
Forgione, Joshua B.; Kojima, Gilbert K.; Hanel, Robert; Mallinson, Mark V.
2014-01-01
The end-to-end verification of a spacecraft photovoltaic power generation system requires light! Specifically, the standard practice for doing so is the Large Area Pulsed Solar Simulation (LAPSS). A LAPSS test can characterize a photovoltaic system's efficiency via its response to rapidly applied impulses of simulated sunlight. However, a Class D program on a constrained budget and schedule may not have the resources to ship an entire satellite for a LAPSS test alone. Such was the case with the Lunar Atmospheric and Dust Environment Explorer (LADEE) program, which was also averse to the risk of hardware damage during shipment. When the Electrical Power System (EPS) team was denied a spacecraft-level LAPSS test, the lack of an end-to-end power generation test elevated to a project-level technical risk. The team pulled together very limited resources to not only eliminate the risk, but build a process to monitor the health of the system through mission operations. We discuss a process for performing a low-cost, end-to-end test of the LADEE photovoltaic system. The approach combines system-level functional test, panel-level performance results, and periodic inspection (and repair) up until launch. Following launch, mission operations tools are utilized to assess system performance based on a scant amount of data. The process starts in manufacturing at the subcontractor. The panel manufacturer provides functional test and LAPSS data on each individual panel. We apply an initial assumption that the per-panel performance is sufficient to meet the power generation requirements. The manufacturer's data is also carried as the performance allocation for each panel during EPS system modeling and initial mission operations. During integration and test, a high-power, professional theater lamp system provides simulated sunlight to each panel on the spacecraft, thereby permitting a true end-to-end system test. A passing test results in a step response to nearly full-rated current
Wachelka, D; Katz, R C
1999-09-01
Test anxiety seems like a benign problem to some people, but it can be potentially serious when it leads to high levels of distress and academic failure in otherwise capable students. Because test anxiety is common in older students with learning disabilities (LD), it is surprising that little research has been done on ways to reduce the distress these students experience in test situations. In this study, we used a randomized pretest-posttest control group design to examine the effectiveness of a cognitive-behavioral treatment for reducing test anxiety and improving academic self-esteem in a cohort (N = 27) of high school and college students with learning disabilities (LD). All of the students participated voluntarily. They were enrolled in classes for students with learning problems. Before the study began, they complained of test anxiety and showed an elevated score on the Test Anxiety Inventory (TAI). Eleven students (85%) completed the 8-week long treatment, which consisted of progressive muscle relaxation, guided imagery, self-instruction training, as well as training in study and test-taking skills. Results showed significant improvement in the treated group which was not evident in an untreated control group (N = 16). Compared to the control group, the treated group showed significant reductions in test anxiety on the TAI, as well as improvement in study skills and academic self-esteem as measured by the Survey of Study Habits and Attitudes, and the school scale of the Coopersmith Self-Esteem Inventory. These results extend the generality of similar studies on reducing test anxiety and improving academic self-esteem in younger students. They also suggest that relief from test anxiety can be expected fairly quickly when cognitive-behavioral methods are used. Additional implications and methodological limitations of the study are discussed.
de la Torre, Jimmy; Lee, Young-Sun
2013-01-01
This article used the Wald test to evaluate the item-level fit of a saturated cognitive diagnosis model (CDM) relative to the fits of the reduced models it subsumes. A simulation study was carried out to examine the Type I error and power of the Wald test in the context of the G-DINA model. Results show that when the sample size is small and a…
de la Torre, Jimmy; Lee, Young-Sun
2013-01-01
This article used the Wald test to evaluate the item-level fit of a saturated cognitive diagnosis model (CDM) relative to the fits of the reduced models it subsumes. A simulation study was carried out to examine the Type I error and power of the Wald test in the context of the G-DINA model. Results show that when the sample size is small and a…
Sapp, Marty
A two-group randomized multivariate analysis of covariance (MANCOVA) was used to investigate the effects of cognitive-behavioral hypnosis in reducing test anxiety and improving academic performance in comparison to a Hawthorne control group. Subjects were enrolled in a rigorous introductory psychology course which covered an entire text in one…
Sapp, Marty
A two-group randomized multivariate analysis of covariance (MANCOVA) was used to investigate the effects of cognitive-behavioral hypnosis in reducing test anxiety and improving academic performance in comparison to a Hawthorne control group. Subjects were enrolled in a rigorous introductory psychology course which covered an entire text in one…
Rodrìguez-Landa, Juan Francisco; Contreras, Carlos M; Bernal-Morales, Blandina; Gutièrrez-Garcìa, Ana G; Saavedra, Margarita
2007-01-01
Since allopregnanolone reduces the total time of immobility in rats submitted to the forced swimming test, we decided to explore whether this neuroactive steroid shares other antidepressant-like actions, such as increasing the neuronal firing rate in the lateral septal nucleus (LSN). In order to discard the influence of the oestrous cycle on immobility and on the firing rate of LSN neurons, all Wistar rats used in the study underwent ovariectomy before treatments. A group of rats received different doses of allopregnanolone (0.5, 1.0, 2.0 and 3.0 mg/kg, i.p.) 1 hour before being forced to swim in order to identify the minimum effective dose diminishing immobility. None of the tested doses of allopregnanolone produced significant changes in motor activity in the open-field test. The minimum dose of allopregnanolone producing a significant reduction in the total time of immobility (pimmobility (pimmobility in the forced swimming test (1.0 mg/kg) significantly (p immobility and LSN firing rate. In conclusion, allopregnanolone produces an antidepressant-like effect in the forced swimming test, associated with an increase in the LSN neuronal firing rate, seemingly mediated by the GABAA receptor.
Leibowitz, Arleen A; Byrnes, Karen; Wynn, Adriane; Farrell, Kevin
2014-03-01
Historically, California supplemented federal funding of HIV prevention and testing so that Californians with HIV could become aware of their infection and obtain lifesaving treatment. However, budget deficits in 2009 led the state to eliminate its supplemental funding for HIV prevention. We analyzed the impact of California's HIV resource allocation change between state fiscal years 2009 and 2011. We found that the number of HIV tests declined 19 percent, from 66,629 to 53,760, in local health jurisdictions with high HIV burden. In low-burden jurisdictions, the number of HIV tests declined 90 percent, from 20,302 to 2,116. New diagnoses fell from 2,434 in 2009 to 2,235 in 2011 (calendar years) in high-burden jurisdictions and from 346 to 327 in low-burden ones. California's budget crunch prompted state and local programs to redirect remaining HIV funds from risk reduction education to testing activities. Thus, the impact of the budget cuts on HIV tests and new HIV diagnoses was smaller than might have been expected given the size of the cuts. As California's fiscal outlook improves, we recommend that the state restore supplemental funding for HIV prevention and testing.
Dam, A. van; Keijsers, G.P.J.; Eling, P.A.T.M.; Becker, E.S.
2011-01-01
It has been suggested that the motivation to spend effort is decreased in burnout patients, resulting in reduced cognitive performance. A question that remains is whether this decreased motivation can be reversed by motivational interventions. We investigated this by examining the effect of a
Co-norming the WAIS-III and WMS-III: Is there a test-order effect on IQ and memory scores?
Zhu, J; Tulsky, D S
2000-11-01
Test-order effect on the WAIS-III and WMS-III scores was evaluated using the WMS-III standardization sample. Participants completed the standardization editions of the WAIS-III and WMS-III in one session, with the tests administered in roughly counterbalanced order. Repeated measure MANOVA analyses were conducted to determine if there was an overall test-order effect for subtest, index, or IQ scores. No significant test-order effects were found for either the WAIS-III index or IQ scores or for the WMS-III index scores. At the subtest level, the majority of the WAIS-III and WMS-III subtests did not show a significant test-order effect. The exceptions were Digit Span and Digit Symbol-Coding on the WAIS-III and Faces II and Logical Memory II on the WMS-III. Although statistically significant test-order effects were found on these subtests, the effect sizes were small. This study indicates that the test-order effect is not a potential threat to the internal validity of the WAIS-III and WMS-III normative data. The practical implications of the current study are discussed.
Douma, Kirsten F L; Smets, Ellen M A; Allain, Dawn C
2016-04-01
Non-genetic health professionals (NGHPs) have insufficient knowledge of cancer genetics, express educational needs and are unprepared to counsel their patients regarding their genetic test results. So far, it is unclear how NGHPs perceive their own communication skills. This study was undertaken to gain insight in their perceptions, attitudes and knowledge. Two publically accessible databases were used to invite NGHPs providing cancer genetic services to complete a questionnaire. The survey assessed: sociodemographic attributes, experience in ordering hereditary cancer genetic testing, attitude, knowledge, perception of communication skills (e.g. information giving, decision-making) and educational needs. Of all respondents (N = 49, response rate 11%), most have a positive view of their own information giving (mean = 53.91, range 13-65) and decision making skills (64-77% depending on topic). NGHPs feel responsible for enabling disease and treatment related behavior (89-91%). However, 20-30% reported difficulties managing patients' emotions and did not see management of long-term emotions as their responsibility. Correct answers on knowledge questions ranged between 41 and 96%. Higher knowledge was associated with more confidence in NGHPs' own communication skills (r(s) = .33, p = 0.03). Although NGHPs have a positive view of their communication skills, they perceive more difficulties managing emotions. The association between less confidence in communication skills and lower knowledge level suggests awareness of knowledge gaps affects confidence. NGHPs might benefit from education about managing client emotions. Further research using observation of actual counselling consultations is needed to investigate the skills of this specific group of providers.
Testing how geophysics can reduce the uncertainty of groundwater model predictions
Christensen, Nikolaj Kruse; Christensen, Steen; Ferre, Ty
2014-01-01
present a modeling platform that can be used to examine the conditions that support the use of each inversion approach for efficient and effective use of all data to constrain hydrologic models. We have developed a synthetic “test-bench environment” to test the advantages and limitations of alternative...... density and coverage. Finally, these synthetic data sets can be interpreted using any hydrogeophysical inversion scheme and the resulting predictions can be compared with predictions from the ‘true’ model. The modular nature of this platform allows for investigations of the role of inversion approach......, data density, data quality, and uncertainty in petrophysical relationships on the accuracy of hydrologic predictions. We will demonstrate the “test-bench” by using a hydrogeological system with a buried valley eroded into an impermeable low-resistivity substratum; the buried valley is filled...
2010-12-06
...The Food and Drug Administration (FDA) is announcing the availability of a document entitled ``Guidance for Industry: Use of Serological Tests To Reduce the Risk of Transmission of Trypanosoma cruzi Infection in Whole Blood and Blood Components Intended for Transfusion'' dated December 2010. The guidance document notifies establishments that manufacture whole blood and blood components......
Reducing Test Anxiety among 12th Grade Students: Iraqi Kurdistan Region/Soran City as an Example
Faqe, Chiayee Khorshid; Moheddin, Kurdistan Rafiq; Kakamad, Karwan Kakabra
2016-01-01
This study aims at reducing test anxiety among twelfth grade students at Soran city high schools. Throughout the study both quantitative and qualitative methods used to collect data. The participants were 450 twelfth grade students in five schools at Soran City-Kurdistan region of Iraq. Non-random purposive sampling because the students needed…
Field tests of biologically active filters have been conducted at groundwater mercury pollution site in Pavlodar, Kazakhstan. The biofilters represented cultures of sulfate-reducing bacteria (SRB) immobilized on claydite imbedded in wells drilled down to basalt clay layer (14-17 ...
Bäuml, Karl-Heinz T.; Holterman, Christoph; Abel, Magdalena
2014-01-01
The testing effect refers to the finding that retrieval practice in comparison to restudy of previously encoded contents can improve memory performance and reduce time-dependent forgetting. Naturally, long retention intervals include both wake and sleep delay, which can influence memory contents differently. In fact, sleep immediately after…
Bäuml, Karl-Heinz T.; Holterman, Christoph; Abel, Magdalena
2014-01-01
The testing effect refers to the finding that retrieval practice in comparison to restudy of previously encoded contents can improve memory performance and reduce time-dependent forgetting. Naturally, long retention intervals include both wake and sleep delay, which can influence memory contents differently. In fact, sleep immediately after…
Datta, Nilanjana; Pautrat, Yan; Rouzé, Cambyse
2016-06-01
Quantum Stein's lemma is a cornerstone of quantum statistics and concerns the problem of correctly identifying a quantum state, given the knowledge that it is one of two specific states (ρ or σ). It was originally derived in the asymptotic i.i.d. setting, in which arbitrarily many (say, n) identical copies of the state (ρ⊗n or σ⊗n) are considered to be available. In this setting, the lemma states that, for any given upper bound on the probability αn of erroneously inferring the state to be σ, the probability βn of erroneously inferring the state to be ρ decays exponentially in n, with the rate of decay converging to the relative entropy of the two states. The second order asymptotics for quantum hypothesis testing, which establishes the speed of convergence of this rate of decay to its limiting value, was derived in the i.i.d. setting independently by Tomamichel and Hayashi, and Li. We extend this result to settings beyond i.i.d. Examples of these include Gibbs states of quantum spin systems (with finite-range, translation-invariant interactions) at high temperatures, and quasi-free states of fermionic lattice gases.
具有单调性非线性项的非线性系统降维观测器设计%The Design of Reduced-order Observer for Systems with Monotone Nonlinearities
朱芳来; 丁宣浩
2007-01-01
Baseed on the discussion about the existence and design method of full-order observer for systems with monotone nonlinearities, a reduced-order observer design method is developed under the assumption that a linear matrix inequality (LMI)has positive definite matrix solution and the reduced-order observer gain matrix is computed by the solution of LMI. By a linear transformation, a reduced-order observer which does not contain the information of the derivative of the system output is provided.A model is simulated and some conclusions are drawn based on the comparison of the results of reduced-order observer to that of full-order observer. The simulation shows that the design method developed by this paper has good performance.
Design and Testing of a Generalized Reduced Gradient Code for Nonlinear Programming
1976-02-01
Penalty Methods.. 34 6.2 Solution of Himmelblau Test Problems ...... 36 K6.3 Comparison with Two Other-NLP Codes ...... 4.1 S6.4i Comparison of Linear vs...effects of m’altiprogramming. ’-g 6.2 Solution of Himmelblau Test Problems I-’ The first twenty-four problems specified in Appendix A of reference [4... Himmelblau (221 implementing an "exact" exterior penalty method, or "Method of Multipliers"--as well as by an earlier version of the code described here
Borg, van der Joanne A.M.; Graat, Lisette; Beerda, Bonne
2017-01-01
Behavioural testing allows to exclude dogs that are fearful and aggressive from the breeding population, but relatively little is known about the effectiveness of such strategies in practice. From 2001 till 2009 parent purebred Dutch Rottweilers had to pass the Socially Acceptable Behaviour
A research program to reduce interior noise in general aviation airplanes. [test methods and results
Roskam, J.; Muirhead, V. U.; Smith, H. W.; Peschier, T. D.; Durenberger, D.; Vandam, K.; Shu, T. C.
1977-01-01
Analytical and semi-empirical methods for determining the transmission of sound through isolated panels and predicting panel transmission loss are described. Test results presented include the influence of plate stiffness and mass and the effects of pressurization and vibration damping materials on sound transmission characteristics. Measured and predicted results are presented in tables and graphs.
The Effect of a Noise Reducing Test Accommodation on Elementary Students with Learning Disabilities
Smith, Gregory W.; Riccomini, Paul J.
2013-01-01
Researchers in the fields of cognitive psychology and education have been studying the negative effects of noise on human performance for almost a century. A new empirical study that builds upon past relevant research on (1) test accommodations and (2) auditory distraction and academic performance was conducted with elementary age students.…
Rajiah, Kingston; Saravanan, Coumaravelou
2014-11-15
To analyze the effect of psychological intervention on reducing performance anxiety and the consequences of the intervention on first-year pharmacy students. In this experimental study, 236 first-year undergraduate pharmacy students from a private university in Malaysia were approached between weeks 5 and 7 of their first semester to participate in the study. The completed responses for the Westside Test Anxiety Scale (WTAS), the Kessler Perceived Distress Scale (PDS), and the Academic Motivation Scale (AMS) were received from 225 students. Out of 225 students, 42 exhibited moderate to high test anxiety according to the WTAS (score ranging from 30 to 39) and were randomly placed into either an experiment group (n=21) or a waiting list control group (n=21). The prevalence of test anxiety among pharmacy students in this study was lower compared to other university students in previous studies. The present study's anxiety management of psychoeducation and systematic education for test anxiety reduced lack of motivation and psychological distress and improved grade point average (GPA). Psychological intervention helped significantly reduce scores of test anxiety, psychological distress, and lack of motivation, and it helped improve students' GPA.
Liu, Y.; Zheng, L.; Pau, G. S. H.
2016-12-01
A careful assessment of the risk associated with geologic CO2 storage is critical to the deployment of large-scale storage projects. While numerical modeling is an indispensable tool for risk assessment, there has been increasing need in considering and addressing uncertainties in the numerical models. However, uncertainty analyses have been significantly hindered by the computational complexity of the model. As a remedy, reduced-order models (ROM), which serve as computationally efficient surrogates for high-fidelity models (HFM), have been employed. The ROM is constructed at the expense of an initial set of HFM simulations, and afterwards can be relied upon to predict the model output values at minimal cost. The ROM presented here is part of National Risk Assessment Program (NRAP) and intends to predict the water quality change in groundwater in response to hypothetical CO2 and brine leakage. The HFM based on which the ROM is derived is a multiphase flow and reactive transport model, with 3-D heterogeneous flow field and complex chemical reactions including aqueous complexation, mineral dissolution/precipitation, adsorption/desorption via surface complexation and cation exchange. Reduced-order modeling techniques based on polynomial basis expansion, such as polynomial chaos expansion (PCE), are widely used in the literature. However, the accuracy of such ROMs can be affected by the sparse structure of the coefficients of the expansion. Failing to identify vanishing polynomial coefficients introduces unnecessary sampling errors, the accumulation of which deteriorates the accuracy of the ROMs. To address this issue, we treat the PCE as a sparse Bayesian learning (SBL) problem, and the sparsity is obtained by detecting and including only the non-zero PCE coefficients one at a time by iteratively selecting the most contributing coefficients. The computational complexity due to predicting the entire 3-D concentration fields is further mitigated by a dimension
Mariam G. Salim
2012-01-01
Full Text Available Although Egypt has already reached the water poverty limit, it possesses a high potential of brackish groundwater available from different aquifers. All Arab countries lie in the best sun-belt region in the world and Egypt has the highest number of sun hours all year round. Solar energy for groundwater desalination is an independent infinite energy resource; it has low running costs and reduces the contribution of greenhouse gases (GHG to global warming. Perfect meteorological conditions and land space are available in remote areas, where solar desalination could supply freshwater for drinking, industry, and for greenhouse agriculture. The present study uses Geographic Information System(s (GIS as a spatial decision support tool to select appropriate sites in Egypt for groundwater solar desalination. Solar radiation, aquifer depth, aquifer salinity, distance from the Delta and the Nile Valley, incidence of flash floods, sand dunes, rock faults, and seawater intrusion in the North Delta, are the criteria that have been taken into consideration in the process of analysis. A specific weight is given to each criterion according to its relative influence on the process of decision making. The results from the application of the presented methodology determine the relative suitability of sites for groundwater solar desalination. These sites are ranked in descending order to help decision-makers in Egypt. The results show that groundwater solar desalination is suitable in remote regions on the North Western Coast, on the North Sinai Coast, and at the Southern Oasis, for reducing greenhouse gases and that it is particularly useful for poor communities suffering from polluted water.
Ballabrera-Poy, Joaquim; Busalacchi, Antonio J.; Murtugudde, Ragu
2000-01-01
A reduced order Kalman Filter, based on a simplification of the Singular Evolutive Extended Kalman (SEEK) filter equations, is used to assimilate observed fields of the surface wind stress, sea surface temperature and sea level into the nonlinear coupled ocean-atmosphere model. The SEEK filter projects the Kalman Filter equations onto a subspace defined by the eigenvalue decomposition of the error forecast matrix, allowing its application to high dimensional systems. The Zebiak and Cane model couples a linear reduced gravity ocean model with a single vertical mode atmospheric model of Zebiak. The compatibility between the simplified physics of the model and each observed variable is studied separately and together. The results show the ability of the model to represent the simultaneous value of the wind stress, SST and sea level, when the fields are limited to the latitude band 10 deg S - 10 deg N. In this first application of the Kalman Filter to a coupled ocean-atmosphere prediction model, the sea level fields are assimilated in terms of the Kelvin and Rossby modes of the thermocline depth anomaly. An estimation of the error of these modes is derived from the projection of an estimation of the sea level error over such modes. This method gives a value of 12 for the error of the Kelvin amplitude, and 6 m of error for the Rossby component of the thermocline depth. The ability of the method to reconstruct the state of the equatorial Pacific and predict its time evolution is demonstrated. The method is shown to be quite robust for predictions I up to six months, and able to predict the onset of the 1997 warm event fifteen months before its occurrence.
Testing how geophysics can reduce the uncertainty of groundwater model predictions
Christensen, Nikolaj Kruse; Christensen, Steen; Ferre, Ty
2014-01-01
information contained in the data. Previous researchers have shown examples for which joint or coupled hydrogeophysical inversion leads to improved use of geophysical and hydrological data. However, to date there are no clear guidelines for when sequential, joint, or coupled inversion should be used. We...... present a modeling platform that can be used to examine the conditions that support the use of each inversion approach for efficient and effective use of all data to constrain hydrologic models. We have developed a synthetic “test-bench environment” to test the advantages and limitations of alternative......, respectively. There is also complete flexibility in the choice of relationships between hydraulic and geophysical properties. Noise can be added to the synthetic hydrologic and geophysical datasets and these exhaustive data sets can be down sampled to represent realistic data sets of varying measurement...
Han, Chang-Fu; Wu, Bo-Hsiung; Lin, Jen-Fin; Chung, Chen-Kuei
2008-08-13
A general mechanical model, which is composed of the mechanical models employed to describe the contact behaviors and deformations arising in all layers (including the substrate), is successfully developed in the present study for multilayer specimens in order to evaluate the contact projected area by a theoretical model, and thus the hardness and reduced modulus, using nanoindentation tests. The governing differential equations for the depth solutions of the indenter tip formed at all layers of the specimen under their contact load are developed individually. The influence of the material properties of the substrate on a multilayer specimen's hardness and reduced modulus at various indentation depths can thus be evaluated. Transition and pop-in occurred at depths near, but still before, the C (top layer)/a-Si (buffer layer) interface and the a-Si/Si (substrate) interface, respectively. Using the present analysis, the depths corresponding to the transition and pop-in behaviors can be predicted effectively.
Fernanda C Dórea
Full Text Available BACKGROUND: Recent focus on earlier detection of pathogen introduction in human and animal populations has led to the development of surveillance systems based on automated monitoring of health data. Real- or near real-time monitoring of pre-diagnostic data requires automated classification of records into syndromes--syndromic surveillance--using algorithms that incorporate medical knowledge in a reliable and efficient way, while remaining comprehensible to end users. METHODS: This paper describes the application of two of machine learning (Naïve Bayes and Decision Trees and rule-based methods to extract syndromic information from laboratory test requests submitted to a veterinary diagnostic laboratory. RESULTS: High performance (F1-macro = 0.9995 was achieved through the use of a rule-based syndrome classifier, based on rule induction followed by manual modification during the construction phase, which also resulted in clear interpretability of the resulting classification process. An unmodified rule induction algorithm achieved an F(1-micro score of 0.979 though this fell to 0.677 when performance for individual classes was averaged in an unweighted manner (F(1-macro, due to the fact that the algorithm failed to learn 3 of the 16 classes from the training set. Decision Trees showed equal interpretability to the rule-based approaches, but achieved an F(1-micro score of 0.923 (falling to 0.311 when classes are given equal weight. A Naïve Bayes classifier learned all classes and achieved high performance (F(1-micro= 0.994 and F(1-macro = .955, however the classification process is not transparent to the domain experts. CONCLUSION: The use of a manually customised rule set allowed for the development of a system for classification of laboratory tests into syndromic groups with very high performance, and high interpretability by the domain experts. Further research is required to develop internal validation rules in order to establish
Huang, Zhijiong; Hu, Yongtao; Zheng, Junyu; Yuan, Zibing; Russell, Armistead G; Ou, Jiamin; Zhong, Zhuangmin
2017-02-24
The traditional reduced-form model (RFM) based on the high-order decoupled direct method (HDDM), is an efficient uncertainty analysis approach for air quality models, but it has large biases in uncertainty propagations due to the limitation of the HDDM in predicting nonlinear responses to large perturbations of model inputs. To overcome the limitation, a new stepwise-based RFM method that combines several sets of local sensitive coefficients under different conditions is proposed. Evaluations reveal that the new RFM improves the prediction of nonlinear responses. The new method is applied to quantify uncertainties in simulated PM2.5 concentrations in the Pearl River Delta (PRD) region of China as a case study. Results show that the average uncertainty range of hourly PM2.5 concentrations is -28% to 57%, which can cover approximately 70% of the observed PM2.5 concentrations, while the traditional RFM underestimates the upper bound of the uncertainty range by 1% to 6%. Using a variance-based method, the PM2.5 boundary conditions and primary PM2.5 emissions are found to be the two major uncertainty sources in PM2.5 simulations. The new RFM better quantifies the uncertainty range in model simulations and can be applied to improve applications that rely on uncertainty information.
Morales S, J.B.; Lopez R, A.; Sanchez B, A.; Sanchez S, R.; Hernandez S, A. [DEPFI, Campus Morelos, en IMTA Jiutepec, Morelos (Mexico)]. e-mail: jms0620@yahoo.com
2003-07-01
The development of a simulator that allows to represent the dynamics of a nucleo electric central, with nuclear reactor of the BWR type, using reduced order models is presented. These models present the characteristics defined by the dominant poles of the system (1) and most of those premature operation transitories in a power station can be reproduced with considerable fidelity if the models are identified with data of plant or references of a code of better estimate like RAMONA, TRAC (2) or RELAP. The models of the simulator are developments or own simplifications starting from the physical laws and retaining the main terms. This work describes the objective of the project and the general specifications of the University student of Nucleo electric simulator with Boiling Water Reactor type (SUN-RAH) as well as the finished parts that fundamentally are the nuclear reactor, the one of steam supply (NSSS), the plant balance (BOP), the main controllers of the plant and the implemented graphic interfaces. The pendent goals as well as the future developments and applications of SUN-RAH are described. (Author)
Pau, G. S. H.; Bisht, G.; Riley, W. J.
2014-09-01
Existing land surface models (LSMs) describe physical and biological processes that occur over a wide range of spatial and temporal scales. For example, biogeochemical and hydrological processes responsible for carbon (CO2, CH4) exchanges with the atmosphere range from the molecular scale (pore-scale O2 consumption) to tens of kilometers (vegetation distribution, river networks). Additionally, many processes within LSMs are nonlinearly coupled (e.g., methane production and soil moisture dynamics), and therefore simple linear upscaling techniques can result in large prediction error. In this paper we applied a reduced-order modeling (ROM) technique known as "proper orthogonal decomposition mapping method" that reconstructs temporally resolved fine-resolution solutions based on coarse-resolution solutions. We developed four different methods and applied them to four study sites in a polygonal tundra landscape near Barrow, Alaska. Coupled surface-subsurface isothermal simulations were performed for summer months (June-September) at fine (0.25 m) and coarse (8 m) horizontal resolutions. We used simulation results from three summer seasons (1998-2000) to build ROMs of the 4-D soil moisture field for the study sites individually (single-site) and aggregated (multi-site). The results indicate that the ROM produced a significant computational speedup (> 103) with very small relative approximation error (constructed at different scales together hierarchically, this method has the potential to efficiently increase the resolution of land models for coupled climate simulations to spatial scales consistent with mechanistic physical process representation.
Kalaroni, Sofia; Tsiaras, Kostas; Economou-Amilli, Athena; Petihakis, George; Politikos, Dimitrios; Triantafyllou, George
2013-04-01
Within the framework of the European project OPEC (Operational Ecology), a data assimilation system was implemented to describe chlorophyll-a concentrations of the North Aegean, as well the impact on the European anchovy (Engraulis encrasicolus) biomass distribution provided by a bioenergetics model, related to the density of three low trophic level functional groups of zooplankton (heterotrophic flagellates, microzooplankton and mesozooplankton). The three-dimensional hydrodynamic-biogeochemical model comprises two on-line coupled sub-models: the Princeton Ocean Model (POM) and the European Regional Seas Ecosystem Model (ERSEM). The assimilation scheme is based on the Singular Evolutive Extended Kalman (SEEK) filter and its variant that uses a fixed correction base (SFEK). For the initialization, SEEK filter uses a reduced order error covariance matrix provided by the dominant Empirical Orthogonal Functions (EOF) of model. The assimilation experiments were performed for year 2003 using SeaWiFS chlorophyll-a data during which the physical model uses the atmospheric forcing obtained from the regional climate model HIRHAM5. The assimilation system is validated by assessing the relevance of the system in fitting the data, the impact of the assimilation on non-observed biochemical parameters and the overall quality of the forecasts.
Using UV photography to reduce use of tanning booths: a test of cognitive mediation.
Gibbons, Frederick X; Gerrard, Meg; Lane, David J; Mahler, Heike I M; Kulik, James A
2005-07-01
Two laboratory studies were conducted in which a new type of intervention was used to reduce ultraviolet radiation (UV) exposure from tanning booth use among college students (Time 1 Ns=70 and 134). The intervention uses UV photography to highlight the damage to facial skin caused by previous UV exposure. When the authors controlled for baseline measures of booth use, students in both studies who viewed their UV photographs reported less booth use at a follow-up session 3-4 weeks later than did students not shown a copy of their photograph. Also, in both studies, the decline in use was significantly mediated by a Tanning Cognition Index composed of variables suggested by the prototype-willingness (prototype) model of health risk: tanning attitudes, tanner prototypes, and willingness to engage in risky UV exposure.
Bourne, Victoria J; McKay, Ryan T
2014-01-01
Reduced strength of lateralisation in patients with schizophrenia has been reported in a number of studies. However the exact nature of this relationship remains unclear. In this study, lateralisation for processing emotional faces was measured using the chimeric faces test and examined in relation to paranoia in a non-clinical sample. For males only, those with higher scores on a paranoia questionnaire had reduced lateralisation for processing negative facial emotion. For females there were no significant relationships. These findings suggest that atypical patterns of lateralisation for processing emotional stimuli may be implicated in, or associated with, increased levels of paranoia.
Building on a solid foundation: SAR and QSAR as a fundamental strategy to reduce animal testing.
Sullivan, K M; Manuppello, J R; Willett, C E
2014-01-01
The development of more efficient, ethical, and effective means of assessing the effects of chemicals on human health and the environment was a lifetime goal of Gilman Veith. His work has provided the foundation for the use of chemical structure for informing toxicological assessment by regulatory agencies the world over. Veith's scientific work influenced the early development of the SAR models in use today at the US Environmental Protection Agency. He was the driving force behind the Organisation for Economic Co-operation and Development QSAR Toolbox. Veith was one of a few early pioneers whose vision led to the linkage of chemical structure and biological activity as a means of predicting adverse apical outcomes (known as a mode of action, or an adverse outcome pathway approach), and he understood at an early stage the power that could be harnessed when combining computational and mechanistic biological approaches as a means of avoiding animal testing. Through the International QSAR Foundation he organized like-minded experts to develop non-animal methods and frameworks for the assessment of chemical hazard and risk for the benefit of public and environmental health. Avoiding animal testing was Gil's passion, and his work helped to initiate the paradigm shift in toxicology that is now rendering this feasible.
Chen, Zhenhua; Chen, Xun; Ying, Fuming; Gu, Junjing; Zhang, Huaiyu; Wu, Wei
2014-10-07
Using the formulas and techniques developed in Papers I and II of this series, the recently developed second-order perturbation theory based on a valence bond self-consistent field reference function (VBPT2) has been extended by using the internally contracted correction wave function. This ansatz strongly reduces the size of the interaction space compared to the uncontracted wave function and thus improves the capability of the VBPT2 method dramatically. Test calculations show that internally contracted VBPT2 using only a small number of reference valence bond functions, can give results as accuracy as the VBPT2 method and other more sophisticated methods such as full configuration interaction and multireference configuration interaction.
Christiansen, Niels Hørbye; Voie, Per Erlend Torbergsen; Høgsberg, Jan Becker
2015-01-01
is by active truncated models. In these models only the very top part of the system is represented by a physical model whereas the behavior of the part below the truncation is calculated by numerical models and accounted for in the physical model by active actuators applying relevant forces to the physical...... model. Hence, in principal it is possible to achieve reliable experimental data for much larger water depths than what the actual depth of the test basin would suggest. However, since the computations must be faster than real time, as the numerical simulations and the physical experiment run...... simultaneously, this method is very demanding in terms of numerical efficiency and computational power. Therefore, this method has not yet proved to be feasible. It has recently been shown how a hybrid method combining classical numerical models and artificial neural networks (ANN) can provide a dramatic...
Bacon, Diana H.
2013-03-31
The National Risk Assessment Partnership (NRAP) consists of 5 U.S DOE national laboratories collaborating to develop a framework for predicting the risks associated with carbon sequestration. The approach taken by NRAP is to divide the system into components, including injection target reservoirs, wellbores, natural pathways including faults and fractures, groundwater and the atmosphere. Next, develop a detailed, physics and chemistry-based model of each component. Using the results of the detailed models, develop efficient, simplified models, termed reduced order models (ROM) for each component. Finally, integrate the component ROMs into a system model that calculates risk profiles for the site. This report details the development of the Groundwater Geochemistry ROM for the Edwards Aquifer at PNNL. The Groundwater Geochemistry ROM for the Edwards Aquifer uses a Wellbore Leakage ROM developed at LANL as input. The detailed model, using the STOMP simulator, covers a 5x8 km area of the Edwards Aquifer near San Antonio, Texas. The model includes heterogeneous hydraulic properties, and equilibrium, kinetic and sorption reactions between groundwater, leaked CO2 gas, brine, and the aquifer carbonate and clay minerals. Latin Hypercube sampling was used to generate 1024 samples of input parameters. For each of these input samples, the STOMP simulator was used to predict the flux of CO2 to the atmosphere, and the volume, length and width of the aquifer where pH was less than the MCL standard, and TDS, arsenic, cadmium and lead exceeded MCL standards. In order to decouple the Wellbore Leakage ROM from the Groundwater Geochemistry ROM, the response surface was transformed to replace Wellbore Leakage ROM input parameters with instantaneous and cumulative CO2 and brine leakage rates. The most sensitive parameters proved to be the CO2 and brine leakage rates from the well, with equilibrium coefficients for calcite and dolomite, as well as the number of illite and kaolinite
Kirkelund, Gunvor Marie; Jensen, Pernille Erland; Villumsen, Arne
2010-01-01
In this study a pilot plant for electrodialytic treatment of municipal solid waste incineration (MSWI) air pollution control (APC) residue was tested and proposed as a treatment method which can lead to reuse of this otherwise hazardous waste. The pilot plant was developed based on a design...... was carbonated by reaction with CO2 under moist conditions prior to electrodialytic treatment. The carbonation alone reduced the leaching of some heavy metals. However, it was not sufficient to reduce the heavy metal or salt leaching to meet the Danish Category 3 guideline levels for waste material reuse...... and could not stand as a treatment method alone. Leaching of both heavy metals and salts were significantly reduced by the electrodialytic treatment for both the raw and carbonated APC residue. In the electrodialytically treated carbonated APC residue only Cr exceeded the Category 3 levels while...
Biocca, Marcello; Conte, Elisa; Pulcini, Patrizio; Marinelli, Enzo; Pochi, Daniele
2011-01-01
The utilization of dressed seed for spring sowing is a widespread practice to control some pests with reduced doses of chemical products. However some insecticides employed in maize seed dressing, namely belonging to the neonicotinoid family and fipronil, have been claimed to play a role in the decline of honeybees (Apis mellifera L.). Pneumatic drills used in maize sowing are charged with contributing to the dispersion of the abrasion dust produced by dressed seeds, favoring the contamination of the honeybee habitat. Different devices similar to air deflectors have been introduced on pneumatic drills in order to reduce dust drift. During previous field tests carried out by the authors during recent years reduction of dust concentration both in the air and at soil surface has been shown as a consequence of their application. As field tests are affected by the variability of environmental parameters (namely wind speed and direction) the results are not always reliable, comparable and of a general validity. This paper refers to a sowing simulation test system in which pneumatic drills can be tested at a fixed point under controlled conditions of the main environmental parameters. In the test area, protected by external influences, artificial wind conditions are created by means of a fan. The drill, suitably placed in the test area, operates the seed distribution "sur place" by means of an electric engine connected to the drill's driving wheel. A 22.5 m long sampling area, leeward with respect to the drill position, has been identified. Along the sampling area a series of Petri dishes has been placed, with the aim of capturing the depositing dust and providing the concentration of the active ingredients (a.i.) at ground level. At the same time, three air samplers with PTFE diskette filters have been used for the detection of the a.i. The test system has been used for the test of a pneumatic drill, equipped with and without air deflectors, using maize seed dressed with
Daily online testing in large classes: boosting college performance while reducing achievement gaps.
Pennebaker, James W; Gosling, Samuel D; Ferrell, Jason D
2013-01-01
An in-class computer-based system, that included daily online testing, was introduced to two large university classes. We examined subsequent improvements in academic performance and reductions in the achievement gaps between lower- and upper-middle class students in academic performance. Students (N = 901) brought laptop computers to classes and took daily quizzes that provided immediate and personalized feedback. Student performance was compared with the same data for traditional classes taught previously by the same instructors (N = 935). Exam performance was approximately half a letter grade above previous semesters, based on comparisons of identical questions asked from earlier years. Students in the experimental classes performed better in other classes, both in the semester they took the course and in subsequent semester classes. The new system resulted in a 50% reduction in the achievement gap as measured by grades among students of different social classes. These findings suggest that frequent consequential quizzing should be used routinely in large lecture courses to improve performance in class and in other concurrent and subsequent courses.
Yang, Kan; Glazer, Stuart; Ousley, Gilbert; Burt, William
2017-01-01
The James Webb Space Telescope (JWST), set to launch in 2018, is NASAs next-generation flagship telescope. The Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) contain all of the optical surfaces and instruments to capture and analyze the telescopes infrared targets. The integrated OTE and ISIM are denoted as OTIS, and will be tested as a single unit in a critical thermal-vacuum test in mid-2017 at NASA Johnson Space Centers Chamber A facility. The payload will be evaluated for workmanship and functionality in a 20K simulated flight environment during this thermal-vacuum test. However, the sheer thermal mass of the OTIS payload as well as the restrictive gradient, rate, and contamination-related constraints placed on test components precludes rapid cooldown or warmup to its steady-state cryo-balance condition. Hardware safety considerations precludes injection of helium gas for free molecular heat transfer. Initial thermal analysis predicted that transient radiative cooldown from ambient temperatures, while meeting all limits and constraints, would take 33.3 days; warmup similarly would take 28.4 days. This paper discusses methods used to reduce transition times from the original predictions through modulation of boundary temperatures and environmental conditions. By optimizing helium shroud transition rates and heater usage, as well as rigorously re-examining previously imposed constraints, savings of up to three days on cooldown and up to a week on warmup can be achieved. The efficiencies gained through these methods allow the JWST thermal test team to create faster cooldown and warmup profiles, thus reducing the overall test duration and cost, while keeping all of the required test operations.
Kodama, Yukinobu; Fumoto, Shintaro; Nishi, Junya; Nakashima, Mikiro; Sasaki, Hitoshi; Nakamura, Junzo; Nishida, Koyo
2008-05-01
The present study was undertaken to elucidate the absorption and distribution characteristics of 5-fluorouracil (5-FU) after its application to the liver surface in rats to examine the possibility of reducing the systemic side effects of this agent. 5-FU was applied to the surface of the liver by employing a cylindrical diffusion cell. Approximately 69% of the dose was absorbed in 360 min. The time course of the change in the amount of 5-FU remaining in the diffusion cell obeyed first-order kinetics. Also, a linear relationship was observed between the apparent permeability coefficient, P app, and the reciprocal of the square root of the molecular weight of several compounds including 5-FU. The estimated P app value of 5-FU was in good agreement with the experimental value. The plasma concentration of 5-FU was low (5-FU was rapidly eliminated from the plasma and could not be detected at 120 min. In the analysis of tissue distribution, the liver was divided into three sites; the region under the diffusion cell attachment site (site 1), the treated lobe excluding site 1 (site 2), and untreated lobes (site 3). After being administered i.v., 5-FU mainly distributed in the kidney, and the concentration in the liver was significantly lower than that in kidney, spleen, or heart. After its application to the liver surface, however, 5-FU preferentially distributed at site 1, and was not detected at the other sites or in other tissues. Thus, these results suggested the possibility of a reduction in the systemic side effect of 5-FU on its application to the liver surface.
1986-01-01
Many users of oral contraceptives (OCs) and potential users misunderstand the risks and benefits of OCs. A recent poll in the US revealed that 3 out of 4 women thought the pill carried substantial health risks. Nearly 2/3 of the women surveyed believe using OCs is at least as risky as childbearing. Family Health International (FHI) recently conducted a world survey of perceptions of OCs. It shows that women in many other countries share US womens negative image of the pill. Women believe in pill-related dangers scientists have never even suspected, much less proven, such as an increased risk of stomach cancer. Yet, many women, especially women in developing countries, are unaware of problems such as cardiovascular disease that are related to OC use, and they are ignorant of the proven health benefits of OCs, such as protection against ovarian and endometrial cancer. Despite the persistence of negative perceptions of the pill, research conducted over the past 30 years has shown that the pill is safe for the great majority of women and, in fact, provides significant health benefits for many users. With the contraceptive effectiveness of the pill established through the early tests, drug companies began steadily lowering the hormone dosages. By 1983, more than half of the OCs sold in the US contained less than 0.5 mg estrogen. Many of the combination OCs now sold have only 0.2 to 0.4 mg estrogen. Eventually, pill researchers learned that OCs containing only progestogen, even in comparatively small doses, also could effectively prevent pregnancy, though not as effectively as pills containing estrogen. The first progestogen-only pills received US Food and Drug Administration approval in 1973. Continued research on OCs shows that the increased risks of cardiovascular diseases actually were almost entirely confined to specific groups women who were over 35 or who both were over 30 and smoked. For the great majority of women, studies showed, the risk of cardiovascular
Tajudin Noor; Bonar Sinaga; TB Nur Ahmad Maulana
2015-01-01
Pecking Order Theory (POT) states that hierarchy fundings based on the cheapest cost coming from internal fund, followed by external fund are needed to determine the capital structure. The research objectives were to examine the concept of POT in agriculture companies listed on Indonesia Stock Exchange in order to decide the capital structure policies as well as to analyse the effects of company’s characteristics to the emitten capital structure. The research used regression analysis with poo...
Barron A, I.; Morales S, J. [Facultad de Ingenieria, Division de Estudios de Posgrado, UNAM, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)], e-mail: isbarron@gmail.com
2009-10-15
The present work shows the analysis of an accident with loss of coolant, LOCA, in the vapor line of economic and simplified boiling water reactor, ESBWR, with reduced order models. The basic understanding of the main phenomena is the benefit of use of reduced order models, being obtained and approximate answer with regard to codes of better estimate. The state equations were identified for the regions in that the vessel is divided, the plant balance and contention, allowed to propose reduced order models programmed in Simulink of Matlab. These models allowed to obtain values of variables involved in the stable state and during a transitory as the accident with lost of coolant, with an error margin according to the type of reduced order models employees.
Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu
2012-08-01
Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.
Task Order Number 5TS5702D035P: Testing Alternative Aircraft and Runway/Taxiway Deicers - Phase 2
2004-06-01
Polymer Matrix Composite Materials 55 10.3 Elastomeric Materials 56 10.4 AircraftWire Insulation "" 58 10.5... Polymer Matrix Composite Shear Stress Test Results 13 Table 8. Polymer Matrix Composite Glass Transition Temperature Test Results """"""’’’’’’’’’’ 14...Table 9. Polymer Matrix Composite Barcol Hardness Test Results 16 Table 10. Polymer Matrix
许锦泉
2000-01-01
Based on the Hückel determinant of conjugated chain polyene，an ordinary formula of reduced order is infered directly only by the use of determinant algebra．Two half－reduced order formulae are deduced thereby．As a result，the relationship of Hückel determinant between the conjugated ring polyene and conjugated chain polyene is clarified．Examples are offered also．